Visits to Kostal Lake are rare due to difficult access. A trail from Clearwater Lake Campground was built in 1971 and originally extended to
McDougall Lake and the west arm of Murtle Lake. The section beyond Kostal Lake has been impassable since the mid-1980s. The rest of the trail was permanently closed by B.C. Parks in 2013 and only the first from the campground as far as the Dragon's Tongue lava flow can still be used. A rigorous access route is still possible by canoe up File Creek, then a cross-country hike over the lava flow. Float planes and helicopters are not allowed to land at Kostal Lake. Landings are permitted at McDougall Lake, 6 km northeast. A permit from B.C. Parks is required. ==Geology==