[GS] Coasting Flooding Question

[Yzman]

So I am trying to understand the requirements for the stonehenge achievement to coastal flood it. Will the ONLY times to flood be the ones that say they are coastal lowlands? I have seen 1 and 3 and they always say coastal lowlands and give a meter. So does that mean that any tile that doesn't say that won't flood ever?

If so this achievement is even more annoying than it already is.