When I told my doctor that I get up about 3-4 times he asked me how much did I pee and I told him a lot. Not just a small trickle. he just told me to not drink anything after 6. yea right. I am thirsty all night long. Doctors are boneheads.
Don't drink excessively at anytime.
If you're working out or training in a hot environment, or at the beach, make sure to drink a lot. But also: get some salt!
Eg, salted peanuts will do if you're at some nice resort.
Otherwise the body won't be able to hold the water, and you will have a head ache when your bound for a night out after sitting on the playa all day.
The same thing goes after a night of heavy drinking: Avoid getting a hangover by eating something with salt in, and drinking a bit of water before sleeping.
Your party doc:
-Hedge