The Boom Lake Trail is in Banff National Park, just after you turn on to the road to Radium (Highway 93). It is an easy 10km round trip hike on a wide, clear trail. It’s more of a walk than a hike, accessible to families, with only 175m of elevation gain. It ends at Boom Lake which is surrounded by mountains still sporting some snow. The water is so clear you can watch the fish swimming past, and one of the fellows on the shore was catching them quite regularly.