Snorkeling is the practice of swimming on or through a body of water while equipped with a diving mask, a shaped breathing tube called a snorkel, swimfins. In cooler waters, a wetsuit may be worn. Use of this equipment allows the snorkeler to observe underwater attractions for extended periods with little effort and to breathe while face-down at the surface. Snorkeling is a popular recreational activity at tropical resort locations; the primary appeal is the opportunity to observe underwater life in a natural setting without the complicated equipment and training required for scuba diving. It appeals to all ages because of how little effort there is, without the exhaled bubbles of scuba-diving equipment, it is the basis of the two surface disciplines of the underwater sport of finswimming. Snorkeling is used by scuba divers when on the surface, in underwater sports such as underwater hockey and underwater rugby, as part of water-based searches conducted by search and rescue teams. Essential equipment includes the snorkel for breathing, a diving mask or swimming goggles for vision.

Swimfins for more efficient propulsion are common. Environmental protection against cold and marine stings and scratches is regionally popular, may be in the form of a wetsuit, diving skins, or rash vest; some snorkellers rely on waterproof sunscreen lotions, but some of these are environmentally damaging. If necessary the snorkeller may wear a weightbelt to facilitate freediving, or an inflatable snorkelling vest, a form of buoyancy aid, for safety. A snorkel is a device used for breathing air from above the surface when the wearer's head is face downwards in the water with the mouth and the nose submerged, it may be either integrated into a swimming or diving mask. The integrated version is only suitable for surface snorkeling, while the separate device may be used for underwater activities such as spearfishing, finswimming, underwater hockey, underwater rugby and for surface breathing with scuba equipment. A swimmer's snorkel is a tube bent into a shape resembling the letter "L" or "J", fitted with a mouthpiece at the lower end and constructed of light metal, rubber or plastic.

The snorkel may come with a rubber loop or a plastic clip enabling the snorkel to be attached to the outside of the head strap of the diving mask. Although the snorkel may be secured by tucking the tube between the mask-strap and the head, this alternative strategy can lead to physical discomfort, mask leakage or snorkel loss. Snorkels constitute respiratory dead space; when the user takes in a fresh breath, some of the exhaled air which remains in the snorkel is inhaled again, reducing the amount of fresh air in the inhaled volume, increasing the risk of a buildup of carbon dioxide in the blood, which can result in hypercapnia. The greater the volume of the tube, the smaller the tidal volume of breathing, the more this problem is exacerbated. A smaller diameter tube reduces the dead volume, but increases resistance to airflow and so increases the work of breathing. Including the internal volume of the mask in the breathing circuit expands the dead space. Occasional exhalation through the nose while snorkeling with a separate snorkel will reduce the buildup of carbon dioxide, may help in keeping the mask clear of water, but in cold water it will increase fogging.

To some extent the effect of dead space can be counteracted by breathing more and as this reduces the dead space ratio and work of breathing. Snorkels come in two orientations: side-mounted; the first snorkel to be patented in 1938 was front-mounted, worn with the tube over the front of the face and secured with a bracket to the diving mask. Front-mounted snorkels proved popular in European snorkeling until the late 1950s, when side-mounted snorkels came into the ascendancy. Front-mounted snorkels experienced a comeback a decade as a piece of competitive swimming equipment to be used in pool workouts and in finswimming races, where they outperform side-mounted snorkels in streamlining. A plain snorkel consists of a tube with a mouthpiece to be inserted between the lips; the barrel is the hollow tube leading from the supply end at the top of the snorkel to the mouthpiece at the bottom. The barrel is made of a rigid material such as plastic, light metal or hard rubber; the bore is the interior chamber of the barrel.

The top of the barrel may be open to the elements or fitted with a valve designed to shut off the air supply from the atmosphere when the top is submerged. There may be a high visibility band around the top to alert other water users of the snorkeller's presence; the simplest way of attaching the snorkel to the head is to slip the top of the barrel between the mask strap and the head. This may cause the mask to leak and alternative means of attachment of the barrel to the head include threading the mask strap a moulded on the barrel, using a figure-8 rubber snorkel keeper pulled down over the barrel, or a rotatable plastic snorkel keeper clipped to the barrel The mouthpiece helps to keep the snorkel in the mouth, it is made of soft and flexible material natural rubber and more silicone or PVC. The commonest of the multiple designs available features a concave flange with two lugs to be gripped between the teeth: The tighter the teeth grip the mouthpiece lugs, the smaller the air gap between the teeth and the harder it will be to breathe.

A tight grip with the teeth can cause jaw fatigue and pain. An integrated snorkel consists of a tube topped with a shut-off valve

Analytics (ice hockey)

In ice hockey, analytics is the analysis of the characteristics of hockey players and teams through the use of statistics and other tools to gain a greater understanding of the effects of their performance. Three used basic statistics in ice hockey analytics are "Corsi" and "Fenwick", both of which use shot attempts to approximate puck possession, "PDO", considered a measure of luck. However, new statistics are being created every year, with "GAR", goals above replacement, "RAPM", regularized adjusted plus-minus, "xG", expected goals, all being created recently in regards to hockey though they have been around in other sports before. GAR seeks to show how many additional goals players individually provided their team due to their skill level, while xG tries to show how many goals a player should be expected to add to their team independent of shooting and goalie talent. Hockey Hall of Fame coach Roger Nielson is credited as being an early pioneer of analytics and used measures of his own invention as early as his tenure with the Peterborough Petes in the late 1960s.

In modern usage, analytics have traditionally been the domain of hockey bloggers and amateur statisticians. They have been adopted by National Hockey League organizations themselves, reached mainstream usage when the NHL partnered with SAP SE to create an "enhanced" statistical package that coincided with the launch of a new website featuring analytical statistics during the 2014–15 season. Corsi, called shot attempts by the NHL, is the sum of shots on missed shots and blocked shots, it is named after coach Jim Corsi, but was developed by an Edmonton Oilers blogger and fan who developed the statistic to better measure the workload of a goaltender during a game. Corsi is used to approximate puck possession – the length of time a player's team controls the puck – and is measured as either a ratio of shot attempts for less shot attempts against, or as a percentage. According to blogger Kent Wilson, most players will have a Corsi For percentage between 40 and 60. A player or team ranked above 55% is considered "elite".

Fenwick, called unblocked shot attempts by the NHL, is a variant of Corsi that counts only shots on goal and missed shots. It is named after blogger Matt Fenwick and is viewed as having a stronger correlation to scoring chances. PDO, called SPSV % by the NHL, is the sum of its save percentage. PDO is measured at strength, based on the theory that most teams will regress toward a sum of 100, is viewed as a proxy for how lucky a team is. According to Wilson, a player or team with a PDO over 102 is "probably not as good as they seem", while a player or team below 98 is better than they appear. PDO is not an acronym for anything, it comes from the online handle of Brian King, the first to propose it, for forums and Counter-Strike. Zone starts is the ratio of how many face-offs a player is on for in the offensive zone relative to the defensive zone. A player who has a high zone start ratio will have increased Corsi numbers due to starting in the offensive zone, while a player with a low zone start ratio will have depressed Corsi numbers.

Strategically, coaches may give their best offensive players more offensive zone starts to try and create extra scoring chances, while a team's best defensive players will have more defensive zone starts. In recent time, the use of zone starts in analysis has decreased, it has been determined. While hockey's analytical statistics can be used to measure in any manpower situation, they are most expressed relative to play at strength; the statistics can be viewed relative to "score effects". Corsi close and Corsi tied, for instance, are restricted to when one team leads by one goal or when the game is tied, respectively; the use of "close" stats is intended to reflect the fact that a team leading a game will tend to play more defensively, meaning the trailing team will take more shot attempts. Corsi close went under scrutiny that it did not predict future goals as well as unadjusted corsi, thus diminishing its value. Methods of weighting each shot by the score situation has taken over as the method to adjust for score effects.

Sabermetrics Sports analytics advanced statistics Introduction to Advanced Hockey Statistics

Independence Seaport Museum

The Independence Seaport Museum was founded in 1961 and is located in the Penn's Landing complex along the Delaware River in Philadelphia, Pennsylvania. The collections at the Independence Seaport Museum document maritime history and culture along the Delaware River. At the museum are two National Historic Landmark ships and the J. Welles Henderson Archives and Library. In 1961, maritime collector J. Welles Henderson felt that Philadelphia's maritime history had been forgotten, was frustrated that his city lacked a maritime museum like those in New England. To rectify this issue, he rented space in the Athenaeum on Washington Square to open the Philadelphia Maritime Museum; the museum housed his personal collection of maritime items. In 1974, the museum moved to 321 Chestnut Street, into a building built in 1898 for the First National Bank. In 1995, the museum moved to Penn's Landing along the Delaware River, after spending $15 million to renovate a building used by the Port of History Museum, which had closed two years earlier.

It was renamed the Independence Seaport Museum. In June 2007, former Independence Seaport Museum president John S. Carter pleaded guilty to charges of fraud and tax evasion from misappropriating about US$2.5 million in funds from the museum. He received a 15-year sentence in federal prison. Carter, president of the museum from 1989 to March 2006, was accused of using money from the museum to buy numerous personal items, including two boats, an espresso machine, a carriage house for his home in Cape Cod between 1997 and 2006. In February 2010, museum officials announced that the cruiser USS Olympia needed $10 to $20 million for hull repairs to prevent her from sinking and would consider transferring her to a new steward; the Seaport Museum held a preservation summit in March 2011, shortly thereafter announced that qualified interested organizations could apply for stewardship of Olympia through a transfer application process vetted by a review panel of historic ship and preservation experts.

In 2014 the Museum announced that it had cancelled plans to seek a new steward and instead would focus its efforts on raising the funds necessary to repair the Ship. In 2014 the Museum received $6 million in funding from the Redevelopment Assistance Capital program, which covered a portion of the repairs. Over the next several years, the Museum was awarded grants from private donors, as well as, federal and state agencies to help cover the preservation costs. In 2017, the Independence Seaport Museum completed the first phase of renovations to the Ship and is working to raise the funds necessary to tow the vessel to a dry-dock facility so that its hull can be repaired. In April 2011, John Brady was named the Seaport Museum's President & CEO. Brady was the longtime director of the Workshop on the Water, the museum's boat shop specializing in the building and restoration of traditional wooden boats. In June 2015, the Museum nearly doubled its endowment after receiving four large donations totaling nearly $13.9 million to help fund museum programs and the restoration to the two historic ships.

In January 2016, the Independence Seaport Museum was given a grant of over $1 million by the William Penn Foundation to fund environmental and clean water programs, as well as, renovations to the dock. In 2017, the Independence Seaport Museum received a grant of $2.6 million from William Penn Foundation to support the River Alive exhibition. In June 2017 the museum opened an exhibit to commemorate the World War I centennial; the World War I USS Olympia exhibit highlights the ship's humanitarian and peace-keeping role in World War I Europe. The exhibit explores the everyday life of sailors aboard the ship, as well as, Olympia's final mission of transporting the remains of the Unknown Soldier from France to Arlington National Cemetery in Washington, DC. In April 2016 the Independence Seaport Museum opened a new exhibit which focuses on Philadelphia and the founding of the United States Navy; as the name suggests and Pirates, examines the conflict between pirates and the United States, features a full-size, waterline model of Diligence of 1797.

Some notable artifacts in the exhibit include a rare 1793 letter from an American taken hostage by pirates, Captain John Barry's octant, a model of the Federal St. Navy Yard recreating Joshua Humphreys' 18th century shipyard. Tides of Freedom: African Presence on the Delaware River, curated by University of Pennsylvania Professor of Sociology and Africana Studies Tukufu Zuberi, opened in May 2013 and explores African-American history along the Delaware River; the exhibit focuses on the slave trade along the Delaware River and the abolitionist movement in Philadelphia, Philadelphia's connection to the underground railroad. The exhibit continues into the modern era, focusing on Jim Civil Rights in Philadelphia. On display at the exhibit are slave shackles and an 18th-century account book that documents the sale of slaves in Philadelphia. Rescues on the River tells the story of maritime disasters along the Delaware River, exploring how tragedy shaped modern maritime safety regulations and led to the formation of the United States Coast Guard.

The exhibit begins with a late 18th-century Revolutionary War-era explosion of a British ship and ends with the 1975 oil tanker collision and resulting fire. Titanic Philadelphians opened in 2012, to commemorate the 100th anniversary of the sinking of RMS Titanic; the exhibit focuses on the 40 Philadelphian passengers of Titanic, their first hand accounts, how their lives were forever altered by the tragedy. On display is a rare first class passenger list, salvaged by Marian Longstreth Thayer who unknowingly had the list in her pocket