The Marietta Islands are still fabulous and a possible destination but between the serious crowding, restricted permitting, and the need to wear a life jacket at all times in the water, one could say the gild is off the lily.
We recommend the much more satisfying alternative of a cruise down the coastline and the chance to lollygag on pristine beaches. There is an excellent chance that you will be the only ones there. Between our own collection of masks and snorkels and those Sef has available, he can accommodate groups up to 8 or 10 people. However, Sefarino speaks very little English.
Sef knows many excellent snorkelling spots and frequently whales and dolphins make themselves known. We have been thrilled to see many of the giant manta rays back in the bay in 2018 after some time of wondering where and if they were still here.