Have you ever tried canoeing with a pair of grown Labs? It's an adventure. One time my ex-dog just got up and walked out of the boat in the middle of a lake. So there we were paddling backwards trying to drag a 90 lb beast back into the boat without tipping it.
Yep, several times. That's how I got my buddies labs to start swimming after they were a year old since they didn't want to go beyond their shoulders otherwise. I paddled them out away from shore and got them to chase the ball out of the canoe. They took to water as labs do and it was hard to keep them out of the water after that.
Have only purposely pulled one back into the canoe once. The lab was getting tired and wanted to continue following us around instead of going back to shore; so I pulled her into the canoe and she laid down in the middle and took a nap. I guess having my buddies kids in the canoe had something to do with it since she was very protective of the youngsters.