GPS

[kancho]

Would a car GPS work underwater as long as it is ina waterproof container and how accurate would it be? Anyone try?

[diversteve]

No, GPS's work on a frequency that's unable to penetrate water.

[cheebaweebie]

The things don't even work well in cloudy weather... You tend to lose signal really easy.

[kancho]

That sucks I wanted to try but if it can't penetrate water then nevermind..

Thanks Everyone

[BSea]

If you want to mark a spot, float a bag from the spot you want marked, and when you surface, you can get the exact GPS co-ordinates. Then you can return later.

[cheebaweebie]

That's a great idea. Would you anchor the bag on the bottom (tie to a rock, etc...) Guess you could use and inflate a balloon and tie to string also (disposable)

[peteg]

You could put the GPS reciever in a small Pelican case and use a foam float attached to a reel, like this guy that does lots of research and mapping in Byron Bay, NSW, Australia:

Simon's gear page (quick and dirty version)

His website is a good diving resource in general.

[MSilvia]

The "line to the surface" option is only accurate if there's no current. Otherwise, you need to know your actual depth, the length of the line you have out, and it's direction so you can triangulate your actual position based on the GPS coordinates. Of course, if a 150' margin of error is acceptable, you may not need to bother, although in that case it might be easier to just take a reading on the boat.

[Matt P]

FYI - not sure if you're diving from a charter boat or not. But, all personal GPS devices are banned on charter boats in this area. They don't want you getting numbers to their fishing\diving spots. You may want to verify with the captain before trying to bring one on board.

[scubamike]

I would love an underwater GPS system...with topography, depth, starting location, compass, etc..

Very unlikely this will ever happen.