Entrance to the bay at Deception Island is through the 230 m (754 ft) narrow entrance called Neptune's Bellows.
Rock formations just under the surface of the water present a navigational hazard.
Due to the protected harbor and the volcanic activity, the island has several microclimates, with water, heated by the volcano, can reach 70°C (158°F). Air temperature can be as hot as 40°C (103°F).