need a compass

[Unregistered]

I wanna buy a compass for relic hunting purposes,but I could not find any where to buy it.do you have any usefull information about different models of compass and is there any disk bigger than 40cm for compass? My searching depth for relic hunting is up to 1.5 merer.Is compass suitable for these depths?
Please send me to [email protected] if possible.
thanks a lot.