I've not tried scuba diving in Lake Kussharo but some tours under the water are arranged these days, different from my adolescence. I've never seen the landscape in the lake.
I have visited this area thousands of times and enjoyed camping but I do not know what can be seen in the lake. I've dived into Lake Shikotsu near Sapporo some times and the scenery under the water is so nice to see.
So many trunks of spruce can be seen at the bottom of Lake Shikotsu. During my wife's absence, I might be able to have time to try that. I think the deities of the lake is not so generous for divers.