I don't believe it's very deep, maybe 10-15ft near the boat launch area (there's a small dock there people fish from) but probably goes down to about 30-40ft near the middle. The map they posted showing the searched areas seems to outline that they've walked the shoreline already. It would be difficult to accidentally fall into that lake though, there are railings, etc, on the walkways. Glen lake is very shallow, and very very weedy. Not very many spots you can get down to the lake at Glen Lake other than the western side where the playground is.