Ennis Lake is a small, shallow reservoir on the Madison River about five miles north of town, formed by the Madison Dam in 1906. The water is much warmer than the river itself — in midsummer it gets to swimmable temperatures, which is unusual at this altitude — and it is the easiest place near Ennis to launch a kayak or stand-up paddleboard. Trout, perch and northern pike all live here; the fishing is less famous than the river but well worth a half day.
There is a free public boat ramp at the south end of the lake. The road around the west side passes several pleasant pull-offs with views back to the Madison Range.