I was out diving in Rockport on the North Shore of Massachusetts one Saturday at site called Old Garden Beach. I was diving with a new diver - a former student who had only recently been certified. We were swimming side by side in about 45 feet of water. I, as usual, had my head practically in the rocks looking for neat critters. All of a sudden, my dive buddy hit me on the shoulder and pointed slightly up and ahead of us. I looked up and almost dropped my regulator out of my mouth. Within a few feet of us slightly above was a large whale swimming past us. The head had already passed us, and we got a good look at its flipper. It was bumpy and notched and itself larger than my dive buddy. Visibility was about 15 feet, and we couldn't see the head anymore, but still couldn't see the tail. It felt like a locomotive endlessly passing us. Finally, with the head out of sight, the tail came into view. We were so close to the whale, that if my dive buddy hadn't stopped me, I would have practically bumped my head on the whale in another kick.
After the dive, we estimated it was about 30 feet long which isn't that large for a whale, but is definitely large compared to divers. We described it at the local dive store and looked at a field guide and came to the conclusion that it probably was a humpback. The scalloped flipper of a humpback is very distinguishable. Also, humpbacks are known to be in that area, although it's hard to believe they would be that close to shore and that shallow.
I constantly get asked why I would dive in the cold waters of New England and what we could possibly see. I always used to give the response of all of the interesting creatures and plant life. I think I have a better response now.