The Cyclops is a player-controlled submarine that is constructed using the Mobile Vehicle Bay. It is equipped with a vehicle bay capable of storing a Seamoth or Prawn Suit and can be modified with a range of different upgrades. These upgrades can help protect the Cyclops against fauna or increase the depth that the Cyclops may go. At 54 meters long, 12 meters wide and 14 meters tall, the Cyclops is the largest vehicle available and capable of diving to depths of 500 meters, or 1700 meters fully upgraded. It can be utilized as a mobile base, capable of being outfitted with furniture and other amenities using the Habitat Builder.

Access is obtained either via the dive chamber located at the bow of the keel or via the docking bay when piloting a Seamoth or Prawn Suit. It is equipped with an onboard AI that will warn the player of danger and a beacon allowing the player to locate it at a distance. If the player chooses to build multiple Cyclops vessels, each will have its own beacon.

The Cyclops functions as a cross between a Seabase and a vehicle: the player can freely walk around inside it, only controlling it when they approach the helm control and "use" it. While controlling the helm, the player is still able to move their viewpoint in a limited arc to look around. The Cyclops takes over the movement controls, with forward and back moving the submarine in that direction, swim up and swim down being used to ascend and descend, and left and right used to turn. It cannot "strafe" sideways, nor can it pitch forward or back as the Seamoth can. The submarine is equipped with three external cameras which are operated via the HUD. These cameras are located on the keel, sail and screw, which in layman's terms are below, above and at the rear of the submarine, respectively. The Cyclops has three speed settings: "slow," "standard" and "flank." As well as speed, each setting affects the amount of noise generated and, in turn, the attention drawn from hostile fauna. A Cyclops is built with a full set of six standard Power Cells inserted into racks of three sockets on either side of the engine, and two wall-mounted Fire Extinguishers, one located next to the damage control console and the other in the engine room.

The Pressure Re-Active Waterproof Nano Suit Mk.III (abbv. Prawn Suit Mk.III) is a bipedal mechanical walker, designed for use in challenging and extreme-pressure environments. Lateral movement is provided by mechanical legs that propel the vehicle along the ground at a top speed of 14 Mph (23 kph), and a pair of boosters on the back of the vehicle provide vertical thrust. The PRAWN Suit also comes with its own beacon, similar to the Cyclops and the Seamoth.

The PRAWN Suit can be used to explore places that are too deep for the Seamoth and too narrow for the Cyclops. It has a base crush depth of 900 meters and can be upgraded to withstand a maximum depth of 1,700 meters, making it one of the most useful deep-sea exploration vehicles (second only to the Cyclops). However, due to its limited mobility in the vertical dimension, it may be wise to use a Cyclops as a transport, as certain biomes such as the Blood Kelp Zone or Underwater Islands may be difficult for the PRAWN Suit to get out of on its own. However, the Grappling arm and Jetpack upgrade greatly enhances the Prawn Suit's mobility and somewhat mitigates this issue. Alternatively, the PRAWN Suit can be used on land for exploration of dangerous areas (keep in mind that the PRAWN Suit is not as mobile on land. The thrusters are nearly useless, even if the Jump Jet Upgrade is equipped). As the suit is immune to heat and poison (though not direct contact with lava), the PRAWN Suit is also great for collecting resources in hazardous areas such as near Lava Geysers or collecting Gas Pods, or for simple protection against most low-to-mid tier predators.

The PRAWN Suit differs from other submersibles in the fact that it sinks in water and is piloted by walking along the seabed, and hence is comparably slower. It does have a jetpack which allows it to launch upwards, but its duration is sorely limited and takes some time to recharge. There are 2 mechanical arms on the PRAWN Suit which are claw arms in their base form and can be upgraded for other options. All arms are activated independently of each other, and the base claw arm can be used either for striking, or for item collection. However, there is a slight delay between clicking and activating the respective claw arm on the suit, so a player may accidentally punch a creature they are trying to collect or miss a falling item. The PRAWN Suit requires energy from Power Cells to operate, which can be interacted with or switched out from the two sockets on either of the shoulder plates. It can be docked in a Cyclops vehicle bay or a Moonpool to recharge the onboard power cells. Unless the power supply is depleted, the player's Oxygen tank will be replenished upon entering, as is the case with the Seamoth and the Cyclops. The vehicle comes equipped with a 24-slot inventory space, accessed from outside in the rear. Any items picked up with the default Claw Arm or drilled with the Drill Arm are automatically placed in the PRAWN Suit's inventory if there is room. If the Propulsion Cannon is used, items can be loaded from the storage space.