i am not sure what you shoot with, but i bought a Nikon d200 (weather-resistant body) just for taking with me on backpacking trips. it cost me about $450 used (KEH) and i have a customized 18-200 lens that i made pretty weather resistant (rubber o-rings and a tight plastic form fitted shell that goes to a UV filter). it would not be great for diving but it has served me great for about 2 years of wind, snow, sand, sea and rain.

another option is using one of Ewa-Marine's (www.ewa-marine.com) waterproof body/lens cases.

and the final suggestion i have is to a rain cover for the camera when you are out in the inclement weather. they are transparent and seem to do a pretty good job of keeping the body and lens dry. i use this set-up for my storm photography. In a pinch, a gallon sized freezer bag works too

easy access is afforded to me by using a kinesis holster system... tho not exactly lightweight