I've had a Channel Islands bag for years that I love. It's got a large main compartment, front pouch, and a bunch of small zipper pockets but it also has a large waterproof dry bag section at the back that could hold equal or more volume than the main area. Unfortunately, it has a few rips and won't last much longer so I'm looking to replace it. Since I work on the water, it's nice being able to pack my clothes in the main part and then toss them in the dry bag section if they're wet to keep everything else dry. It fits under the seat on airplanes so I don't need to pay for carryon or checked bag, so it's really great all around. I checked with Channel Islands and it doesn't look like they sell anything similar any more (this bag is probably close to 20yrs old). Is there anything similar on the market?