Where to see honu on Maui without crowding them
Honu are Hawaiian green sea turtles, and Maui is one of the best places in the islands to see them.
Hookipa, late afternoon
The north shore beach is the reliable one. They haul out onto the sand in the late afternoon, sometimes a dozen or more at once, and there is a lookout above the beach where you can watch the whole thing without going anywhere near them.
That lookout is the best seat, not the consolation prize.
If you would rather be in the water
Black Rock in Kaanapali and Maluaka Beach in Makena are the snorkeling spots.

The rule, and why it is also the better plan
Ten feet on land, ten feet in the water.
They are protected under both federal and state law, and Maui has people who will tell you so if you crowd them. But set the law aside for a second: watching a honu come up for air a few feet away, on its terms, beats anything you would get by swimming at one. The photo you were chasing is worse than the moment you gave up to get it.
They are also called guardians of the sea in Hawaiian tradition, which lands differently once you have floated next to one.