[Redwulf__32]

Coast Align only takes actual coastlines into consideration - not stretches of open water.

Thank you Redwulf__32 but I don't understand the meaning of your answer, could you explain me in other way?

I understood that you had "mountains of water" far from the coastline - Coast Align will not flatten these water areas to the surrounding sea level. Coast Align flattens the coast (land part) to the level of the water.

....hope this clarifies...
Redwulf__32