But that close call did not look to be bothering him in the slightest as he relaxed in the sea.
The couple were enjoying some downtime at the Baths in Virgin Gorda, a popular tourist attraction on the island of Virgin Gorda in the British Virgin Islands in the Caribbean.
The baths are giant boulders — or batholiths — brought to the surface by volcanic eruptions. They form tranquil pools.
Koepka was showing off the body that has seen him become golf's strongest man.
The ripped American can bench almost 150kg and is expected to soon appear naked in ESPN's Body Issue.
However, his extreme conditioning and diet has come at a cost.
Koepka existed on a measly 1800-calorie-a-day diet to get lean and was blasted by respected Golf Channel pundit and former PGA Tour star Brandel Chamblee for jeopardising his golf in order to look good.
It was Chamblee who was made to eat his words, though, with Koepka saying after a first-round six-under 66 at Augusta: "Well, I lift all the time, I lift too many weights and I'm too big to play golf. And then when I lose weight, I'm too small.
"Listen, I'm going to make me happy. I don't care what anybody else says. I'm doing it for me and obviously it seems to work."
Koepka would go on to finish 12-under in the season's first major and he will defend his US PGA crown next month at Bethpage Black in New York.
