The Harmony Super sponge will help keep the inside of your boat dry. This synthetic sponge has a cellulose cover, absorbs up to a liter of water, is resistant to mildew, and is machine washable. It's durable, compact and features a handy tie-in tether sewn to the corner. It can be used in conjunction with a bilge pump on on its own.
Soaks up a lot of water and seems to be holding up well. I like that it has a tether.
Best bilge sponge out there. Great ACK customer service as usual.