Comment by FearNotDaniel

I'm obviously missing some facts about the region, as per the OP's hypothesis, because a naive look at the map suggests that even without Crimea, Russia already has coastline onto the Black Sea between its borders with Ukraine and Georgia... there must be a strong reason in favour of invading another country rather than developing ports on the land they already have, if the goal is simply "control over the Black Sea and trade access to the Mediterranean Sea".