I'm not a strong swimmer but have done some snorkelling on The Great Barrer Reef. I am looking forward to a trip to Maui next year – can anyone clarify what is the best spot on the west coast of Maui for snorkelling (NOT DIVING)? We also have a couple of days in Honolulu if Oahu is better.

Starting in the north these are our favorites - Honolua Bay - rocky entrance , may have to pay access fee and parking may be hard to find, have had dolphins show up, if lots of recent rain water will be cloudy due to creek runoff but still worth all the trouble. Kahekili Beach Park - just north of Ka'anapali Beach - have heard whale song here in the right season - lovely reef. Black Rock - northern end of Ka'anapali Beach near the Shearton , beach entrance can be surgy, great wall, turtles out around the point. Olowalu - beach entrance, can be quite shallow(low tide) and crowded as the reef is close to the road. Farther south the Kama'ole beaches have some snorkeling spots and can also be busy as it is such easy snorkeling. Keawakapu Beach - at the north end go out around the point, fairly quiet but near the boat launch so keep an eye out. The point between Mokapu and Ulua beaches is another favorite - small but usually see turtles. Polo Beach - another lovely spot with easy entrance. Palauea Beach (White Rock) - the points on both eds of this beach offers good snorkeling, the southern point has a larger area to explore. Chang's Beach, Five Graves/Five Caves in front of the Makena Surf is another area with some great coral and lots of turtles. Black Sand Beach (Oneuli Beach) - getting in may be difficult as it is shallow but then head out and go south and snorkel along the cliff, again turtles galore - you can see them feeding on the grasses along the shore. Ahihi Cove, the Fishbowl and the Aquarium are among the best Maui has to offer but I do believe they are off limits at the moment(part of the marine park) to allow for a breather - check when you get there as they lift the ban by then. Compared to Maui, Oahu does not have the same possibilities for snorkeling. Enjoy!!

Get "The Ultimate Kauai Guidebook" by Wizard Publications. It's one of the best guides I've seen for anywhere, and includes beach-by-beach descriptions of the possibilities. In West Maui, you will be in crowds a lot. Honolua is hands down the best in that area. You can access it as described above, or walk down steps at Mokule'ia Beach and snorkel around the point IF IT'S CALM.
In the Kihei area, if you aren't a great snorkeler, you can park in the beach access for the Makena Surf condos, and snorkel around the point to Chang's Beach, where you can rest. Then, you can go on to Five Graves, and the point the Snorkel Cruises call Turtle Town. Using the Makena Surf access lets you use their showers. Chang's also has parking and access if the tiny Makena Surf lot is full.
The very best snorkeling is at the end of the road in the Marine Reserve. As noted, areas like the Fishbowl and Aquarium are closed, although Ahihi Cove was open in summer of 2009. It rewarded long swims, but there was a lot to see right away. See [http://www.shorediving.com/Earth/Hawaii/Maui/index.htm] for a site-by-site description.
Maui has two main issues for snorkelers. First is the fierce wind, that usually blows things out very thoroughly by noon. Second is the huge crowds. If you put in at, say Makena Surf or Makena Landing and swim out along the shore to the point, you have about 15 minutes to enjoy it before huge catamaran after huge catamaran start piling in. The dump their mobs of snorkelers, all in color-matched fluorescent floatation devices, and have guides ride herd around them in kayaks. Pretty soon, tourist butts outnumber fish tails by a big margin. The horror! The horror!
By all means invest in some cheap reef shoes at Long's Drugs or Costco. They're great for letting you enter at one spot, swim along a lot of coast, and then carry your fins as you walk on the road back to where you started. Don't expect too much from Maui (I wouldn't go back because of the wind and the ridiculous crowds), but it's OK. It definitely beats Oahu!