Stalin showed interest in the Dardanelles because it connected the

Black Sea and Mediterranean Sea

Explanation:

The Dardanelles have been of great strategic importance for a very long time, and they still continue to be. Stalin wanted to get it under his control because it was going to put the Soviet Union in an excellent situation, be it economically or military. The importance of the Dardanelles is so big because it is the place that connects the Mediterranean Sea with the Black Sea. Also, it is also the place that separates Europe and Asia, and of the most important trading routes. Despite the interest Stalin had, it never came to a situation that the Soviets attacked to capture this place.

Aegean and Black Seas

Explanation:

usatestprep answer