The Seamoth is a small, versatile one-person submersible that is capable of carrying you to the biomes fast while protecting you from the attacking agrresive creatures. Unlike the Cyclops the Seamoth does not require rare metals to construct, what you will need however is a survival knife, O2 tank (1 or 2), scanner, and the Fabricator. The materials needed are 1 Titanium Ingot, 1 Power Cell, 2 Glass, Lubricant, and Lead.
To be able to construct the Seamoth you will first need to find and scan fragments to get its blueprint. Several can be found in the numerous wrecks in the Grassy Plateaus surrounding Lifepod 5, in the Aurora, and occasionally even on islands. Once you have all the required parts and its blueprint you will need a Mobile Vehicle Bay to build it.
The Seamoth comes equipped with a locator beacon that produces an image on the HUD showing the distance of the vehicle from the player. There are a number of upgrades and modifications that can be added that enhance performance and durability, these include additional storage, Seamoth Sonar, Seamoth Perimeter Defense System, Hull Reinforcement, Engine Efficiency Module, Seamoth Solar Charger and Torpedo System. However before you can build these upgrades you must first find their blueprint.