My ideas, vol. 2
More Trees/Plant, you need fruit.
Elevator, needs: Rope, Wood, and Scrap, also it's not a modern elevator, it's a platform with a spool and crank to lift.
I would say shark trap, but i think there should be a shark proof diving cage.
A Shark Defense system, basically a hinged plank with a spike, that is kept up with a rope, when the shark bites.. it breaks the rope making the plank swing down, and stab the shark .
A tethered foundation, to push out... and have another mini raft.
Anchoring the raft, items will slow down.
Building on my deep sea diving from last time, if you don't have an anchor... then use a tethering point, instead of the raft being tethered to the ground.. you're tethered to the raft, also there should be sunken rafts, planes and ships, to get better stuff like weapons.
Signs.
Taller pillars (just put a pillar on a pillar to extend).
Console commands.
Getting Crabs, and lobsters and such from the ocean floor.
and that's it