Yep, Huggies make swim nappies or some companies make reuseable cloth ones too. Was talking to another mum today who uses a cloth swim nappy and she said they work fine for BF poo too

Thanks for that tip Danni, we're mostly in heated pools indoors, so go have a warm shower afterwards. A physio attached to the hospital he was born at does baby-swim from 8 weeks, so thinking I might sign him up as he loves the water already