Koh Ma is a tiny island northwest of Koh Phangan which connected to Phangan island by a sand bank at low tide. The island and this sandy path are emblematic images of Koh Phangan. On one side you have Mae Haad beach and on the right, Koh Ma, more wild, more preserved. Surrounded by reefs, Koh Ma is also a good site for snorkeling. I did not do it but you can climb to the top of Koh Ma island and enjoy the panoramic views. But take good shoes.
A big and luxurious resort is under construction (October 2017) right in front of Koh Ma which is probably not good news for the future of this beautiful part of Koh Phangan so do not delay your visit there.