I find the baby swim classes invaluable, mostly in terms of knowing what to do with a baby in the water and safety skills.
The first time we took my child swimming was on holiday aged 3 months and I was terrified, worried she'd drown, no idea how to hold her in a pool, certainly wouldn't have dreamed of putting her under the water.
Baby swimming classes mean that she goes underwater every week, and my husband and I are now very confident doing underwater with her when abroad etc.
We know different holds, we've got some fun rhymes to do with her, she's confident coming up to the surface, and she can hold onto the edge (now aged 1). She's great at kicking, and so confident in the water.
But also she loves it. It's her favourite thing of the week, and we both really look forward to it. She gets really excited whenever we get to the pool. We've made good friends with the other mums, we have a nice lunch afterwards. Also definitely there is the brilliant long nap after swimming (although nursery get the rewards of that now, but when she was tiny it was great).
She started at about 4 months, and we still go now even though she's at nursery and it's at an awkward time. It's super expensive, but would be one of the last things we gave up.
I never bothered with the underwater photoshoot though.