Only skimmed a few of these, but had to say that these goggles changed everything for DS when he was learning to swim (they also come in adult sizes and tinted/non-tinted). http://www.aquasphereswim.com/us/products/seal_kid_clr_transblu.html

They fit on the face, not in the eye sockets, so they're more comfortable, and even more importantly, they have quick release tabs for on/off so they don't pull hair, aren't too tight, etc. Once he had these, underwater was no problem. He now will swim without goggles, but this was a big first step in swim lessons.