When I was a kid, I used to catch tadpoles and treefrogs in a frog pond near my house in Maple Ridge. I was delighted, as I recall, to find leeches therein. My friends and I would actually put the leeches on our skin and let them start to feed, then experiment with the best ways of removing them. The easiest, most surefire leech-repellent was fire. Hold a flame near them, or touch them with the hot metal edge of your lighter, and they would curl up and drop off, eager to get away.
The leeches were nowhere near as big as the ones in the picture accompanying this article, but they were still pretty cool.
Too bad the pond was paved over and turned into condos - it's been gone for around 25 years. I wonder where the decendents of those frogs mate now (assuming any are still alive?).