Captain Marvin's is MUCH closer than 3/4 of a mile. My wife was comfortable (other than being thirsty) with our walk from the Nautilus and we passed Captain Marvin's on the way back. She has problems some times with her legs cramping and a walk of one mile after being in air conditioning and sitting down would have been very difficult, so I know it wasn't that far. We found Grand Cayman to be fairly compact in terms of the shopping area and port area. As I recall, Captain Marvin's was just a few hundred yards (a bit more than a quarter mile in my estimation) from the tender dock. Quite an easy walk even in the heat.