Question about diapers to swim in

We are taking our 4 month old to Hawaii and I was wondering what kind of diapers you use under their swimsuit. Do they make swimming diapers for infants or do they only make them for toddlers? I've also read about reusable swim diapers or something like that. Is anyone familiar with them and how do they work?

[kijip]

Disp. swim diapers are like little training pants. They are usually brightly colored and you can get them for infants as small as 14 pounds (or so). The one we use are Huggies. They are sold in packs of 16 for a about $15. You don't need a suimsuit over them but you could use one.

Reusable swim diapers are like little elastic cloth diaper covers. You do not use another diaper inside of it. They often have a cute pattern on them so you don't need a swimsuit. The key is the tight elastic waist and leg holes. They are designed to keep stool out of the water. I got mine at a little baby shop for about $4 but I have seen them on eBay, in maternity shops and from cloth diaper services.

Hope this helps!