Diving in high mountain lakes??

[swmarc]

So, I will be certified in about two weeks and am interested in diving in some high mountain lakes surrounding Mt. St. Helens. in particular a lake known as castle lake which is about 2500ft in elevation. Keep in mind I wont be doing this for at least another year or so, but it is something that I have been thinking about. The water in this lake is the clearest I have ever seen. It is absolutely amazing.
What are the precautions that you need to consider when diving at high altitude? The only thing that I can think of is that your depth gauge wouldn't read at all if is was calibrated for sea level.

[RonFrank]

IMO 2500 feet is NOT a high mountain lake? Just keep your profile conservative, and you will be fine. Your depth gauge will not be impacted if it's digital. If it's analog, it will.

You will however need to determine what needs to be done to dive these area's. Sometimes nothing, but sometimes you will be restricted from diving it period. Talk to the local or national park service to determine if diving where you are going is allowed, and what is necessary.

[Noboundaries]

Take the Altitude Certification class or your AOW with an Altitude Adventure dive. There are quite a few factors to consider before diving at altitude. For example, when you arrive at the lake, you are basically starting a surface interval from your "dive" in the air at the lower elevation. You are literally off gassing nitrogen at the higher elevation from the drive up to lower pressure. You have to determine your pressure group and how long you have to wait before you can start diving.

There are also calculations you have to perform on your depth readings to adjust to the elevation. If diving with a computer, does your computer automatically adapt to the higher elevation? If so, what computer startup procedures are required?

There's more to consider. Don't just go diving unless you want to hurt yourself.

[swmarc]

IMO 2500 feet is NOT a high mountain lake?

well its high to me What else would you call it? Its at the base of a volcano. I have already looked into what is allowed at the lake and the only restriction I can find concerns motorized boats, which are prohibited.

[nwbobber]

I have emailed the national monument folks and they don't respond regarding diving in Coldwater or Castle lake. I take that as a green light. How are you going to get your gear down to castle? Thats a hell of a hike. I wouldn't mind giving coldwater a go, but all I'm willing to take to Castle is a fishing rod and a tent.
It should be an interesting dive though, I wonder what the outlet side looks like.

Bob

[fdog]

IMO 2500 feet is NOT a high mountain lake?<snip>

Exactly the first thought that went through my head.

Since we dive routinely in Lake Tahoe at 6200' without issues, 2500' is a far cry from "high altitude", and unless you really try (intentional deco) you won't get into trouble.

IIRC the US Navy tables don't even reccomend altitude considerations below 2300'. Flipping through my NOAA Diving Manual, the depth corrections are very minor - at an altitude of 3000', a 60 FSW dive is treated as if you'd been to 65'.

As Ron said, dive conservatively and it will be a non-issue. I'd be more worried about lugging my gear to the water and back.


All the best, James

[The_DivePirate]

As far as high mountian lake, anything over 1000' is considered an altitude dive. There are many differences in diving at altitude vs. sea lvl. diving. Mostly due too atmospheric pressures and nitrogen off gassing in those situations. Get yourself an altitude cert. and look for a theoretical depth conversion table that will help figure depths and stops. If you have any other Q's about diving at altitude I'd be glad too help, I live at 4500' and 50% of my diving is done at altitude.
Good luck,
Joe

[The_DivePirate]

I have emailed the national monument folks and they don't respond regarding diving in Coldwater or Castle lake. I take that as a green light. How are you going to get your gear down to castle? Thats a hell of a hike. I wouldn't mind giving coldwater a go, but all I'm willing to take to Castle is a fishing rod and a tent.
It should be an interesting dive though, I wonder what the outlet side looks like.

Bob

Try diving Crater lake. Not sure about castle, but the trail into Crater is basically a mile long one way and has approx. 1000' in elavation drop, with only foot traffic allowed. The water level is at 6176', so the dive is figured as a 7000' dive. I could look back through my log book, but I believe the water temp was 42*. Diving at altitude is NOT no big deal, you have real issues that can incure due too the altitude and stresses of the cold water that comes with high lakes. DIVE SAFE!!!

Joe

[swmarc]

I have emailed the national monument folks and they don't respond regarding diving in Coldwater or Castle lake. I take that as a green light. How are you going to get your gear down to castle? Thats a hell of a hike. I wouldn't mind giving coldwater a go, but all I'm willing to take to Castle is a fishing rod and a tent.
It should be an interesting dive though, I wonder what the outlet side looks like.

Bob

Part of the fun would be getting my gear down to the water. I actually considered Coldwater first but I have spent more time at Castle. Who knows this is a long ways off and I am just starting to get into diving.

[gearhound]

Get drysuit certified. Mountain lakes are cold. Keep your ascents slow. And learn different finning techniques (especially the frog kick) to keep silt down. Those are my suggestions.