One time I went canoeing in the mangrove swamps at John Pennekamp Coral Reef State Park, Florida, with a companion who had never been in a canoe before. Once he got the hang of it, he wanted nothing but to go as fast as we could through the green labyrinth.
Hardly knowing where we were going, we went down a little path barely wider than the canoe. Deeper and deeper into the unmarked swamp, the path grew smaller and smaller, until we were ducking under the mangroves as they closed in around us.
Suddenly, the tiny path emerged onto the main boat channel, just as one of the large tour boats passed.
My companion was unaware of the danger, and there was no time to explain. I wedged my paddle against a prop-root and shoved the canoe out into the open channel as quickly as I could, to get some maneuvering room. Then I whirled the canoe through a 90-degree right turn, just in time to meet the wake bow-on.
Another instant, and we'd have gone swimming!