...more bowline trivia:

It's a knife knot, meaning that it can bind under heavy load so that it cannot be untied.

An unusual attribute of a bowline is that it can fall apart underwater. If you use a bowline underwater in a manner that it will shake, alternatively tightening up and going slack, such as under a buoy, it will fail. The original use of a bowline, on the forward edge of a square sail when hard on the wind, is a similar situation, but out of the water. Lobstermen and longliners don't use bowlines.

- MacEntyre