Where in the Hawaiian islands is the best place to snorkel? How does it compare to Cozumel?

I don't know the BEST place to snorkle, because Hawaii is chalked full of great snorkling places. The snorkling in Maui around Kaupalua is especially nice, but like I said before there are wonderful places all over Hawaii. One tip, if you can bring your own snorkle gear, it can save you loads of money.

I'll avoid the comparison trap.

On Maui: Honuloa Bay, Kapalua Bay in the summer.

On Kaua`i: Poipu Beach, Anini Beach, Ke'e Beach and Makua (Tunnels) Beach.

-Bill

Kealakekua Bay on the Big Island is generally considered to have some of the best snorkeling in the state.

I've never snorkeled in Cozumel so I can't offer a comparison.

From our experiences, I'd have to say we think that Kealakekua Bay is the best (Capt. Cook Monument area) as well, although the Maui and Kauai recommendations above are great areas too. That area is more difficult to get to (generally accessed by kayak or tour boat) but it seems to have fewer people there due to the limited access.