I have that one, bought for offshore yacht cruising, especially night passages, and I have taken it on a remote bushwalk. I'd hate to have to deploy it (even at the best of times) in the surf, even though you just have to extend the antenna and press the button. Then you have to keep the antenna pointing to the sky. Fine if you're heading out to sea in a rip or current or offshore wind, but otherwise you'd be smashed on the rocks by the time help arrived. I'll just avoid spots that dodgy as I become more risk averse with age.

Apple Watch maybe? A guy in Byron got rescued about 1 km out to sea after being caught in a rip. He selected the SOS function on the watch and was found by emergency services. From memory he was body surfing. One lucky dude.

Mark H has a good story about that exact scenario. Good thinking!!!