unobstructed
Unobstructed in Russian is незагороженный, незакрытый, незаслонённый.
But they sound too technical and I recommend that you avoid using such terms, favoring instead their counterparts without the "не", like прямой, открытый и т.п.

I've also seen "с беспрепятственным видом на море", which is technically okay, but still sounds a bit rough (just like any other attempt to translate it into Russian in this type of thing, tho).