Hi Steve, I’ve never dove Lake McDonald but I do know people do and love it. Apparantly there is an under water Forrest of sorts. It’s from a landslide that pushed trees, root and all, into the water closer to where Sprague Creek comes in to the lake. Once past the rocks it does have a sandy bottom that can get stirred up. But usually very clear and cold. Dry suit needed unless you are okay with a wet suit but water is deep and cold so they advise staying closer to the shorelines. You can solo I believe but dive flags are mandatory. Theres a fire in the park and its closed my the Lodge but Apgar is open on the lake. Just here for this week? Cuz McGregor Lake is a good diving lake as well and Yellow Bay in Flathead. Where are you coming in from?

Thanks for the info. And sorry for delayed response, service is terrible on easrside of glacier. Right no planning to go to lake McDonald Saturday, if the road reopens. We are in from Alabama. Leaving Monday. I’ll save the Flathead for another trip. Cheers!