Commuting - Swim Bag / Pannier?

I'm looking for a bag, trunk, or pannier that I can use to transport swim equipment to/from the local pool. I want something that has a separate pocket to carry wet items in, and can be easily detached from the bike and carried around. The Arkell panniers have a mesh pocket on the outside that might do, but they're a little pricey. Any other suggestions?

I don't know much about panniers (I am very new to commuting), but you could probably rig a small triathlon bag to your rack. Don't know if that helps, but it is something to think about if there isn't anything else out there.

I've looked around but I can't find any swim bags or backpacks that are designed to fit on a bike. I think I'm going to go with the Arkel Bug (http://www.girlbike.com/reviews/arkelbug.html) pannier/backpack, which Arkel says can hold wet items between the main compartment and its outer shell. Expensive ($109) but it can do double duty for commuting.

What about just putting the wet items in a plastic bag of some sort (reuse a bag from a retail store, grocery store, or garbage bag)?

Edit to add: And then put the plastic bag in your panniers. Your items won't dry out on the ride to your destination, but it's something to consider.

My panniers have two main compartments on each bag (there's also a couple of smaller compartment and a packable net used for attaching a sleeping bag or other big items to the side of the pannier). I put wet stuff in a plastic bag and slide the bag into one of the compartments. I keep my dry stuff in the other.

I'm looking for a bag, trunk, or pannier that I can use to transport swim equipment to/from the local pool. I want something that has a separate pocket to carry wet items in, and can be easily detached from the bike and carried around. The Arkell panniers have a mesh pocket on the outside that might do, but they're a little pricey. Any other suggestions?
Not sure what you mean by pricey and not sure which Arkels your looking at. I have a set of Jandd Mountainer painers got them for like $80 one side has a mesh pocket like you mentioned, I can throw wet stuff in there and if it's lycra or a quick dry material and hasn't been packed to tightly it will usually dry nicely by the time I reach my destination.

If you check on some trunk bags, and some handle bar bags you should be able to find mesh pockets. Handlebar bags usually have mesh on the side so it wouldn't be big enough for a towel. Arkel makes some great stuff, but my customer service experience with Jandd usually has many checking out their products first.

And finally, you might want to check out one of the trunk/pannier combination bags. They sit on the rack and have a fold out pannier on each side. Unless your touring and want stuff to dry while you ride, you can use one side for wet stuff, and the other and middle for dry. Seems like the least expensive most flexible option. I have two different Trek models on my kids bikes and it's amazing how much stuff they can pack in the things, and still bungie a sleeping bag to the top. I like the newer interchange bag the best, it fits in a special rack, but you just push a button and it lifts right off ready to go in a hurry, but it still has straps if you have a rack and don't want to swap it out. Pretty sure Topeak has a similar model too. With the bungies on the tops where you can put wet stuff to dry if that is your goal might work for you.

go to Nashbar.com, they have a pannier that will convert to a backpack and it is only 30.00

Serratus make a fine set of panniers in 40 and 56 L that have mesh pockets. They are sold at MEC stores. Follow the links in the cycling section. Website:www.mec.ca