A few years ago, we had to negotiate to get the brunette twin NEAR a pool -- forget going in it. This girl wouldn't even sit on the deck. For their first birthday party, the blond twin happily played in the water with anyone who would hold her. The brunette twin wouldn't leave my brother's living room. I spent the nearly entire party with her in the house.
We're lucky that both my brothers have pools. In the past, if we decided to go swimming, the blond twin would run to get her bathing suit. The brunette twin wouldn't even put it in the bag. In fact, she'd check the bag to make sure we didn't bring it.
The entire drive, we'd discuss what was going to happen. "Sissy is going to swim with Mommy. You are going to sit with Daddy. No, Daddy will not go in the pool. No, you are not going in the pool." This went on for the better part of two summers.
Last year the brunette twin was willing to stand in the pool, but only because she could touch the bottom. (One of my brothers' has an in-ground pool with a shallow end.) As long as she could touch the bottom, she was willing to play.
Two days ago she decided to stand on the edge of the pool and jump in. We were thrilled! She's gone from not being willing to bring her bathing suit to the pool to jumping in all by herself.
Now, of course, she wants to go off the diving board. I told her she needs to learn to swim before she starts diving. She's taking this as a personal challenge, so I have no doubts she'll be diving soon.