Carry-on luggage that fins fit in?

[gearboy]

I only see three reasons to put something in a carry-on: (1) I MUST HAVE it upon arrival, (2) It is TOO FRAGILE for the possible treatment of checked baggage, and (3) it is TOO VALUABLE to put in someone else's care for fear of theft.
I don't see that fins are in any of the three categories. #3 is often mitigatable with extra declarations and possible payments.
I don't consider avoidance of checked-bag fees a good reason....there are other ways to avoid those fees (certain credit cards, for example).

Two of my last three trips were going straight from the airport to the live aboard. On one we were rerouted midway through, with most people ending up quite anxious about any of the checked gear following us. If your trip has no chance to replace lost gear, reason number one applies.

As a general rule, I hate to check bags, though my wife hates to carry things, so when you travel together, I still end up having to hang out at the baggage carousel.