Add a new world title that contains super deep water, that cannot replaced with landfill so players is forced to use cargo ships and not cheating with landfill and trains.
- there should be some limitations to land like 3000 (or less/more) titles till the first deep water
- another suggestion deep water cause damage to the ships (just a little) because large waves ofc! and maybe need more fuel -> Can lead to a possibility where some swimming platforms are needed to get like an tanking and repairing station.

I second this feature. This would be awesome.

+1. Except for the damage. I was about to report the same idea.

My thinking though was that there could be 2 landfills and a new tile:

Cheap landfill: only works near the shore in shallow water. You throw a little dirt in the water and you are above sea level and have normal ground.

Large landfill: much more expensive. You first have to fill in all that ocean so it takes a lot of resources. Can only be placed on normal water.

Landing / Swimming Platform: It's a path tile like stone path and relatively cheap. Takes wood and maybe empty barrels to create and can be placed on shallow water or water but not deep water. Should be relatively cheap. Once placed pumps, inserters, belts, power poles, combinators, lamps can be placed on it. But not assemblers or furnaces (or tanks?). It's not a replacement for landfill but just for building docks.

Deep water can't be filled at all. It's basically bottomless. And with the big deep sea waves a landing platform would be unstable. Deep water should start far from shore and maybe not in the starting area at all.