If the icon on the map is close to right, it should be inside Ukraine territorial waters and it's shallow there, but I don't know the exact depth of water.
If the big picture objective is to get rid of Putin and his regime in Russia, then helping the Ukrainians to break his army and eject him completely from their country while blowing up his bridge at Kerch is a way to do it, make his failure and humiliation complete. Once his army in Ukraine is broken and destroyed, he will be powerless and Ukraine will be active in Georgia and Belarus, causing as much mayhem and revolution as they can. Belarus and Ukraine could end up in a military alliance against Russia, if they too kick Vlad out and change their government, then he will have his buffer between Russia and NATO, but it will be hostile and armed to the teeth by NATO, with warehouses of arms ready to be shipped in the EU. While both Finland and Sweden will become NATO members. This is a result of Vlad's threats, weakness and having most of his army tied down in Ukraine. It's a good time for them to join NATO and both are real assets and not burdens, Vlad's atrocities in Ukraine helped move public opinion in both countries a lot.
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Ukraine War: Turkey to limit access to strait