Hi Rachel,
Sorry, I wish I had seen this before... Well, here's something you might want to try next time...
I use this with or without a hood and it's the only thing that works very well for me even without a hood! I also have about collar length hair - I can tuck it behind my ears but not in a ponytail.
It's one of those plastic spiky scrunchies. I hope you know what I'm talking about. Teens used to wear them around 5 years ago. You wear it from your front hairline, down behind your ears, and to the nape of your neck, where it locks together. The spikes stretch out like a comb and comb into your hairline, holding every hair in place. If you have some tiny hairs, don't push it back too much or you can still use a bobby pin to make sure.
This works extremely well, and is usually in place even after 2 dives! :dazzler1:
Bonus: This looks decent and neat on. If you keep this comb-like band on until your hair dries, it will give you some waves in your hair and it will look fairly nice for your apres-dive get-together...
These bands can usually be found at accessory shops, flea markets, and dollar stores. Good luck!