I understand your situation; I have both a Pentax K-R and an older *ist DL and don't want to take either fishing.
I just recently picked up a Pentax Stylus Tough 3000. Newegg.com has them on sale for $99. Like most waterproof cameras, the pictures are not as sharp as even a good point and shoot, let alone a SLR with good glass. However for the longest time waterproof cameras hovered in the $200 to $300 range, so I picked up this Stylus tough as soon as I checked a few reviews.
Not glowing reviews, but check the waterproof cameras 3x that price and they will be similar..
Newegg has nice fast shipping, so getting it for the weekend should not be a problem.
I would suggest getting some extra batteries as they are small and low capacity, though tests show the camera delivered its rated 160 shots. I opted to get 2 off-brand LI-42 "equivalent" batteries for around $2.50 each from an Amazon.com reseller. I would also recommend getting a separate charger as you have to charge the battery in the camera with a proprietary USB cable otherwise. The off brand charger ran me around $5, also bought from a Amazon.com reseller.
I had the camera out this weekend and was content with the picture quality..