There are a number of these "moon gates" all over Bermuda. I think they were borrowed from Japanese culture around the late 19th century (according to Wikipedia, anyway).

The sign next to this one by the ship reads, "Couples who kiss under our moongates... will, according to local legend, be assured a long and happy life together. Walk through one of our lovely limestone archways, make a wish and look forward to a joyful and prosperous future."

Sometime during the last week someone has scratched next to this, "DULL SHIT." Maybe they meant to add another loop to make it, "BULL SHIT," but it really does just look like, "DULL SHIT," left by some vandal bored out of their mind by local traditions.