Another beach on the Norther part of Koh Phangan, Mae Haad, is one of the more unique beaches, as it has a smaller island (Mae Haad) attached to the larger beach with a sandbar, which you can walk to over the sandbar. Really beautiful and something you must experience at least once, while you are here. The sandbar can be very shallow or waist deep, depending on the tides. And Mae Haad Island is very laid back, has descent snorkeling and an abandoned resort to explore around, as a path on Mae Haad goes by it.
The main beach is a bit built up it is still a beauty and the commercial resorts that are there do offer amenities not found on other beaches.