The Giant's Lair is a location in the Zahhab Region Depths in Endless Ocean 2. It is located near the seafloor in the North Crevasse, at coordinates C-2 Northeast, and it doubles as the entrance to Osiris's Courtyard, which contains the wreck of the HD-9 Submarine.
Like the Chimney Forest in the South Crevasse, it is home to hydrothermal vents that encrust the seafloor in some areas (just at lower numbers in this location). Luckily for the player, none of these vents are active, and they never become active at any point in the game.
The creature that gives this area its name, the Giant Squid, is the main sea life that can be found here, both during the main story and then again once the player returns here. However, it is not a permanent resident of the area, and does not return directly to the Lair after leaving (instead patrolling the North Crevasse), leaving the local life to consist of smaller creatures, including Firefly Squid and Glass Squid, under zoom-mode spots on the walls.