The Airport Tunnel, also known as the Sepulveda Boulevard Tunnel, is a highway tunnel in Los Angeles, carrying Sepulveda Boulevard underneath the two runways (25L/25R) and taxiways on the south side of the Los Angeles International Airport (LAX). This section of Sepulveda is a part of California State Route 1. The tunnel was the first in the United States to run under an airport runway.

Sepulveda Boulevard is a major street and transportation corridor in the City of Los Angeles and several other cities in western Los Angeles County, California. The street parallels Interstate 405 for much of its route. Portions of Sepulveda Boulevard between Manhattan Beach and Los Angeles International Airport (LAX) are designated as part of State Route 1.