Crater Lake

Trapped in the caldera of extinct volcano Mt. Mazama, Oregon’s only National Park beckons divers with its indigo blue and vertical walls. Famous for its distinctive blue water Crater Lake attracts visitors from around the world who marvel at the surface colors. The same magnificence greets divers below the surface. Expect shades of blues and violets you have perhaps never experienced before.
Crater Lake is classed as an oligotrophic lake so you will not be seeing many fish. I have seen a few, they are shy Brown Trout mostly. The Atlas of Oregon Lakes (1985) rates the transparency of Crater Lake at 95.1 feet. However the USGS reports:

The record clarity of Crater Lake was measured at a depth of 41 m (134 ft) in August 1994. The lake clarity is measured with a secchi disk, a black and white disk lowered into the water with a cable. Its exceptional clarity is mainly due to its isolation from streams and rivers. There is no incoming stream to bring any organic materials, sediments, or chemicals to pollute the lake, although natural plankton in the lake and wind-borne pollen have seasonal effects on water clarity. Particulate materials and chemicals are mainly introduced into the lake through precipitation and run-off of the calderal walls. The caldera wall is composed of volcanic rocks that do not react with or dissolve easily in cold water, although warm water escaping from the caldera floor adds a small amount of dissolved solids.

I believe the latest bathymetric survey of Crater Lake was completed in 2003 as the USGS reports:

The maximum depth of Crater Lake recorded at the time of the July 2000 multibeam survey was 594 m ( 1,949 ft). The lake level had an elevation of 1,883 m (6,178 ft) above sea level at the time of the survey. The lake level of Crater Lake fluctuates according to the climate. (

long crater lake

Crater Lake


As of the summer of ’03 the Park Service no longer requires preregistration for diving Crater Lake. That adds convenience and safety for those who enter the park from the north entrance. However, the park service does expect divers to have in their possession their certification cards and to apply altitude diving rules. A floating dive flag must be towed above divers in the water. I have had casual conversations with Park Rangers, and their questions reflected knowledge of the hazards of diving the lake. If one is not versed in applying altitude diving rules I suggest one get some training before diving Crater Lake for a couple of reasons. First, since one passes over the rim at over 7000 feet one must calculate the dive at 8000 feet! Second (and I will emphasize this again) this is a rigorous dive — with strenuous exercise before and after. Trust the Force on this. In addition, a diver needs experience with controlling open water vertical descents and excellent buoyancy control. It is not a good beginner’s dive.

The only access down to the lake is via Cleetwood Cove Trail on the north side of the lake. The parking lot area is slightly over 7000 feet so as I said before the dive must be planned at 8000 ft. The trail is a steep gravel hiking trail. There is about 1000 ft of elevation change in about 3/4 of a mile. The Park Service does not allow any wheels to be used on the trail. This is a rigorous hike without a heavy pack! Please, one should not do this if one is not reasonably fit. I load all of my equipment, including an old 72 cu ft tank and weights, on a sturdy aluminum backpack. The whole shebang weighs about 110 lbs. I hump this down the trail to the dive site and then split the load for the hike out. I have seen people hike out with their full down load with white flecks at the corners of their mouths. Remember, this is not level ground and one is at 7000 ft. Dalton’s law of gasses means there is less oxygen to get and one can easily experience hypoxia. This is rigorous! Stay hydrated! Take your time! Dive a conservative profile!

When one reaches the bottom of the trail, go past the boathouse toward the privies. Go around below the toilets and you will be on the top of a cliff with boulder access down to the water. Carefully pass your gear down and suit up in the boulders. One may enter the water on a slight shelf, but about 10 feet out it is a vertical wall — I mean vertical! Straight down to about 95 or 100 feet and then a steep slope into the abyss. Remember, this lake is over 1900 feet deep. There is nowhere at this dive site to stop and adjust buoyancy on the bottom! Divers must be skilled and control their descents carefully. Avoid banging into the wall or finning against the wall — the fine sediment will silt the vis and other divers won’t appreciate it! I like to turn left after entering from the boulder patch and swim kind of southeast admiring the absolute beauty of the wall formations. If I have gotten down early enough to avoid the breeze rippling the surface, I have been able to clearly see trees standing up above the cliff on the wall of the caldera. When one looks down into the abyss, notice the different shades of purple and violet. There are some great photo opportunities along the wall if the vis is undisturbed. At the end of the dive, be sure to allow a 3 minute safety stop at the appropriate depth for the altitude. Please dive a conservative profile.

What I normally do in the summer is set up an Altitude Diver Specialty class on a weekend. We do our two training dives in Waldo Lake and then move our camp up to a higher elevation on Saturday afternoon to acclimate. We then go into the national park on Sunday morning and knock off the Crater Lake dive. By acclimating at about 6000 feet, we are able to add a margin of safety to our dive.