You could get one of those waterproof underwater pouch's for about $10 on eBay.
Most are IPX8 certified and can be submerged up to 20 feet underwater continuously.
Some come as an arm band, others can be attached to your wetsuit.
Ideal for key remote and phone.
Link here as example:
http://www.ebay.com.au/itm/Waterproo...Swohax14_FIgCg