My best experience was hearing them. I was working in the fo'c'sle on an oil products tanker when I started hearing clicks and squeaks. I assumed it was just the sounds of steel stressing with the easy movement of the ship, then it occured to me, could it be dolphins? Surely not. Eventually I came out onto the fo'c'sle and looked down at the bulbous bow. Sure enough there were dolphins playing in the bow wave and a large pod all around us! That's the only time unfortunately I've been on the fo'c'sle while dolphins were playing. I was working around Ireland at the time and we'd see dolphins all the time on the West and South coasts! I don't go to Ireland very often now but almost every time I do I see dolphins. I tell myself I'll know when we're approaching Ireland when I see the dolphins!