Just wondering...if you are in the ocean and want a drink of some refreshing tap water..is it hard to drink underwater? with a straw?
Sure you can, but first a bit of background... When I was 12 and just became certified, I was a member of the Underwater Club of Canada (UCC). Each year, the Club had a display at the Canadian National Exhibition (CNE) in Toronto. It's considered a pretty big deal up here, attracting more than 5 million visitors in an 18 day period.
The UCC owned a large steel tank (on a flat-bed trailer) with glass windows (now owned by the Ontario Underwater Council). A crowd would gather to see the SCUBA demonstration on the hour, which lasted about 10 minutes. This was 1965 and diving was seen as a bit off the beaten path. Being a kid and not having school, I was one of the divers that were available to participate. One of the 'Club Sponsors' was a soda company called "Crush." Orange Crush was quite popular at that time. It was an ideal choice, as it wasn't overly carbonated, so it didn't generate gas, which could be a problem in-front of a crowd...
I ended up drinking more soft drinks underwater than I'm sure was healthy, but I was a kid who loved soft drinks so it was great. Usually one bottle was shared between two divers per show.
Before you do this in OW, be sure to try this first on-land and in the pool. I don't suspect that you will be drinking from a bottle but the drill was to open the bottle upside down and cover the opening with your thumb. After the regulator is removed, place the bottle to your mouth and
blow gently into the bottle. The result is that the liquid will be driven into your mouth (and down your throat). It takes some practice, but you can consume (note that I didn't say
drink) about 4 ounces a second (2-3 secs for a normal sized bottle). The drill was to drink half, cover the bottle and give it to the other diver to finish.
Being serious though, if you hydrate before and after the dive, drinking underwater isn't necessary. It's fun to try in the pool though...