Santa Cruz Island, also known as Indefatigable Island and by other names, is the most populous and second-largest island in the Galápagos Islands, Ecuador. Situated in the middle of the group, Santa Cruz is a shield volcano with an area of 986 km2 (381 sq mi) and a maximum altitude of 864 m (2,835 ft). The seat of Santa Cruz Canton is Puerto Ayora on Santa Cruz. The island's total population is around 18,000 with those living in smaller villages chiefly working in agriculture and cattle raising.

The Galápagos Islands are an archipelago of volcanic islands in the Eastern Pacific, located around the Equator 900 km (560 mi) west of South America. They form the Galápagos Province of the Republic of Ecuador, with a population of slightly over 33,000 (2020). The province is divided into the cantons of San Cristóbal, Santa Cruz, and Isabela, the three most populated islands in the chain. The Galápagos are famous for their large number of endemic species, which were studied by Charles Darwin in the 1830s and inspired his theory of evolution by means of natural selection. All of these islands are protected as part of Ecuador's Galápagos National Park and Marine Reserve.