The sea forts appear to be abandoned military forts erected years prior to the player's character's marooning. Each structure is left in a state of disarray, with shelves and different containers tipped over and different supplies strewn about the area. Each individual fort holds a bridge between it and the next fort for ease of relocation. Most sea forts' bridges, however, are broken, either by deliberate means or from extensive decomposition, but they can be sprint-jumped across to reach the other individual forts.
Most individual forts consist of 4 different floors:
- A low platform with a ladder for access to or from the sea;
- A more open floor above that connects with the other forts over bridges that may be broken;
- Several rooms containing different supplies, and;
- A roof with a toolbox.
Currently, there are two different layouts for each individual fort. Aside from this, each sea fort's structure and layout is almost exactly the same, but each contain different randomly-generated supplies, although it seems that there will always be one (or more) part(s) of the boat motor, one or more jerrycans, beans, a bucket, and a torch or flashlight, among other supplies. Sea forts can be built on, meaning that foundations and campfires can be placed on them, if the player ever decides to take shelter inside an individual structure.
When exploring each fort, one must mind any sudden drops that may be present in the forts; missing panels and open hatches can be found around a fort's structure, and one such layout holds a deep well-like hole in the center of one of the lower rooms. At times, there will be a separate platform underneath it; in other cases, it will lead straight to the ocean. Falling from such heights can cause the player to bleed or otherwise suffer minor injuries. The broken bridges branching off of each fort may also be a potential hazard, as one may easily miscalculate the distance required to jump when crossing.
- They are mostly located in areas that are deep enough to be considered Deep Sea biomes, deep sea-type creatures (e.g. great white sharks, humpback whales, marlin, etc.) spawn around them as of v0.03.H1
- Similar to buoys, sea forts are structures in the water that cannot be seen from afar. They can only be seen when the player is close enough to them.
- The sea forts are based on the Maunsell sea forts found off the coast of England.
- Potato plants have the potential of spawning on the roof of one or more of the buildings, making the sea forts a potential for permanent bases.
- The railings on the sea forts were simply for show - if the player attempted to walk into them, they would simply pass through and possibly fall into the ocean below. As such, care was to be taken when navigating the sea forts. This may have been fixed in a hotfix.
- Prior to v0.03.H1, sea forts were quite common; this trait was altered to balance the game.
- Occasionally, when paddling to a sea fort, the raft can suddenly be dragged to the bottom of the sea and glitched into the seabed. It is unknown whether this is caused by lag or a scripting error. The bug can be remedied by approaching the sea fort from a different direction.
- Extreme lag can be experienced near or on these forts (computer type does not seem to matter; even faster computers can be affected). Most of the time, the quickest remedy is by simply saving the game. It will run smoothly until the game is reloaded, where the process will have to be repeated.
- When it rained, the particles could be seen falling through the fort. This has been fixed as of v0.03.H1.
- Sea forts will suddenly disappear if the player paddles or swims too far away; the forts are still there but do not load. This makes sea forts extremely hard to find if they are not marked.