If there’s any group of people who most appreciate the unique ecosystem of Oregon’s Crater Lake, it’s probably scuba divers. After all, divers devote huge amounts of time and energy to observing and enjoying marine life. But, ironically, those divers could also represent a serious threat to the lake, which is the deepest and clearest in the country.

Officials are closing off Crater Lake to scuba divers while they work on a plan to protect it from invasive species. The lake has become an increasingly popular destination for divers since a segment about diving there aired on the Oregon Public Broadcasting show “Oregon Field Guide” last year. Ecologists worry that scuba divers could bring quagga mussels, spiny water fleas or a virus that is deadly to fish into the lake. Any of these species, or a number of others like them, could prove disastrous for the 1,943 foot-deep lake.

Diving the lake is such a demanding proposition that until now divers hadn’t been considered a big threat. To reach the lake, they must carry 80 pounds or more of gear down a 1,000-foot slope (no wheeled carriers allowed), take a boat to an island and then hike for another half hour over volcanic debris. The lake is also so high up that the risk of the “bends” is higher than in most places. One diving instructor told The Oregonian that he and his fellow divers camp at 6,000 feet to adjust to the altitude before attempting a dive in the lake.

Once there, though, divers can see volcanic formations, tunnels and thick layers of peat moss.

The park plans to reopen the lake to diving sometime next year and will probably require divers to get permits and follow various restrictions.

Main photo credit: @Michael/Flickr