If you belong to a club with a swimming pool, make friends with the lifeguards. At the end of the season, they have a lot of items in their lost and found. Towels, goggles, swimsuits, flip flops, pool toys, cameras, sunscreen .. it’s a bonanza of summer goodies. On the last day the pool is open they toss it all in the dumpster. Ask them if you can go through the stash before they toss it. Any items you can’t use yourself, you can take to Goodwill or the Salvation Army.
Even if you don’t belong to a club with a pool, you could call and ask if you could pick up these items to take to your local thrift store.