Underwater Habitat - Basic Types of Habitats

Basic Types of Habitats

Underwater habitats are designed to operate in two fundamental modes.

1. Open to ambient pressure via a moon pool, meaning the air pressure inside the habitat equals underwater pressure at the same level, such as SEALAB, and which makes entry and exit easy as there is no physical barrier other than the moon pool water surface
2. Closed to the sea by hatches, with internal air pressure less than ambient pressure and at or closer to atmospheric pressure; entry or exit to the sea requires passing through hatches and an airlock

A third or composite type has compartments of both types within the same habitat structure and connected via airlocks, such as Aquarius (laboratory).