Extremely confused with this word.
I have the following words: primorskii, na poberezh'e i and another word that I always forget but express the idea of seaside, I think priberzhennyi
How I will say:
1. Across the seaside road there are 5 hotels.
2. This is a seaside home.
3. The seaside area.

Also how I will say: This house is located on the heights outside Moscow. When I say heights I don't mean mountain. A height might be 100 meters from the seaside level. It just shows altitudinal difference from an area lower from it.