I have double checked the mods and they are all white but i can't get it to work.

Not sure what you mean sorry. Can you post screenshots please?

Try start a normal map. It should be Sea Block

I had similar issue: selecting only Seablock, confirm+restart, starting new game gives vanilla map. Only after few additional restarts (of whole game process) it properly loaded (and map settings finally stopped showing sliders for ore patches). I guess some common QoL mod causes issues (like Bottleneck or RecipeBook) so it is probably a good idea to enable only Seablock for game start, and only later add other stuff.

Bottleneck and Recipe Book both work fine with Sea Block. If you're not getting a Sea Block map, open your mod list and see which mods are listed in red. Something will be conflicting but it won't be either of those two.