I'm stuck at the Every second counts quest (chapter 2, mission 1). The game wants me to build a deep sea warehouse on the free site of the underwater island. But it says: "you can only have one deep sea warehouse per underwater island" and I don't have any other deep sea warehouses, so I'm pretty much stuck. What to do?
Just build the deep sea warehouse, to do this you need to put the required materials (8 building modules and 4 tools) on a sub, submerge it and make it move to the underwater island, then the option to build the warehouse appears.
What the game means by
is that you can only have 1 deep sea warehouse on each underwater island.