"We all use on dive boats"? There are dive ops still handing out those one-use plastic bottles of water on their boats? WTF is that about? I wouldn't dive with such an op. I prefer the good 'ole big insulated water cooler with a spout on the bottom just like you see on the back of every sizable construction crew's truck or trailer. A bag of purified ice goes in and then it gets filled with purified water. I'd say 90% of the divers on boats that use a cooler bring their own water bottles with them that they refill over and over again throughout their vacation everywhere. Virtually no one ever uses the disposable plastic cups that are available. The reality is a dive op can't offer wax paper cups and cones effectively on their boats because they get wet and the humid/wet environment renders them useless in a day or two.
I'm guessing you won't share the name of the dive op you use that is still handing out plastic water bottles that get 1/4-1/2 drank and then are found laying all over the place in the boat to be thrown away. Tell your dive op to get an insulated water cooler and end the plastic personal bottled water BS or you'll find a new dive op. That sends a STRONG message that just may be heard unless that op caters to a dive clientele that cares less about the environment and prefers to see their selfish/arrogant demands met... God forbid they drink water out of a spout from a common cooler.
Before you make assumptions like that, why not inquire with your dive op how the bottles are disposed of? My crew brings the plastic bottles back to our bodega and I have a recycling bin. Every Friday, Hazlo Hoy picks them up for recycling.
I would love to be able to have a cooler with a spout, but there is not a secure way that we've found to secure them in the small boats.
We did have the individual souvenir water bottles that were given to each guest at the beginning of the trip at one time, but there were issues with the supplier here. We are in the process of getting more and should have them in the next 30 - 45 days.