typebug- I have a ring sling made of Solarveil that I wear my babies in often during summer. It is great for the swimming pool. However, Solarveil isn't made anymore, but you can still find slings and such online. I also bought a wrap from an etsy seller that was made of a mesh material, but it kind of dug into my skin a bit (and I couldn't avoid that because it needed to be wrapped that tightly in order to support baby properly) and wasn't as comfortable to wear as the sling.
I am a HUGE fan of the Beco Butterfly. I wore both of my girls in mine all the time. It supports a really tiny baby's head better than the Ergo, IMO.