The Cyclops is a vehicle in Subnautica. It is a submarine and can be built in the Mobile Vehicle Bay. However, you have to explore the depths of planet 4546B in order to get it. Here is how to build the Subnautica Cyclops and the upgrades you can give it.
The Cyclops can store a lot, including a Prawn Suit and a Seamoth. It can also be used as a moving base of operations and can be equipped with furniture.