Get in a car, cab, taxi or bus and go to Hunama (I know my spelling is wrong)Bay.
Water is so clear and fish so abundant that you can seethem from the parking lot 100 feet above the beach.
American Express travel has desks at several downtown hotels and will book excursions with legitamate companies for you.
Take The Bus to Hanamma Bay think it costs 1.50 and it drops you off right near the entrance and picks you up. I think it runs every hour but check the bus schedules. If you don't have your own snorkel gear you can rent it down in the Bay.
If you go to Hanauma Bay, also go around the large cliff that protruds out into the sea on yout left if you are facing the ocean. You can walk around this cliff at sea level. On the other side in the cove there are some lava tubes where the waves rush up. One lg. one is called "the toilet bowl". It's been 12 yrs. since we saw it, but it seems to me it was around 6 or 7 ft. deep. Sort of just like a round toilet bowl. The seawater rises in it as the waves come itn. That's when you get in. The water level then falls and you go down with it, then up again as the water rises! You ride up & down, up & down. Really fun and different! As for the snorkeling at Hanauma Bay, it was terrific! I have heard that it now gets so crowded that sometimes they have to close it to visitors for a while if you get there too late in the day, and wait until some people leave to get in. I think it's a State Park.
Also be aware that Hanauma Bay was (at least in the past couple of years) shutting down one or two days a week to let the bay take a break from people. Check with the state park people if they're still doing that.
You also will want to get there early, early, early or you won't find a place to park if you're renting a car. If you take The Bus out to the bay and they dump you off at the top of the hill there is a shuttle bus that willt ake you down the hill and you can rent snorkle gear at the bay.
Do yourself a favor and read the bulletin board near the pavilion before you get into the water. If the Witches Brew is churning that day take care. It is at the mouth of the bay and can suck you out into the rip current. Bye, bye Honey!