I noticed suggestions about looking into integrated air horns. Well, here's the problem with those, if you're out of air the horn doesn't work!
I have a sub-duck for my Zeagle set up. Since it sounds a bit like a duck, it's not practical at the surface. It's used primarily for getting the attention of students during a class while underwater. I also have a whistle on my gear. The whistle is a Fox-40 (plus it works UW). It's primary use is at the surface for emergencies. Also, the sub-duck is a great turtle deterrant when spearfishing!
Trust me when I tell you that nearby boaters will assuredly start looking when you honk on a Fox-40 repeatedly in an emergency, provided they're not zooming by. If you're considering either of these options, the whistle is best for at the surface, but some of the air integrated signal devices, such as air hammers, do work well at the surface.
I have a sub-duck for my Zeagle set up. Since it sounds a bit like a duck, it's not practical at the surface. It's used primarily for getting the attention of students during a class while underwater. I also have a whistle on my gear. The whistle is a Fox-40 (plus it works UW). It's primary use is at the surface for emergencies. Also, the sub-duck is a great turtle deterrant when spearfishing!
Trust me when I tell you that nearby boaters will assuredly start looking when you honk on a Fox-40 repeatedly in an emergency, provided they're not zooming by. If you're considering either of these options, the whistle is best for at the surface, but some of the air integrated signal devices, such as air hammers, do work well at the surface.