Plain coconut water is literally just the water on the inside of a coconut. So if you can get coconuts at your grocery store you can get coconut water. I also found this recipe on how to extract and flavor the water: http://www.eatnapplay.net/2013/03/04/make-your-own-coconut-water/.
About Celebrity Solstice. Celebrity Solstice is a large ship, carrying 2850 passengers and 1246 crew, and sails from Sydney, Australia and Auckland, New Zealand.
P&O Cruises is a British/American cruise line based at Carnival House in Southampton, England, operated by Carnival UK and owned by Carnival Corporation & plc.&O first introduced passenger services in 1844, advertising sea tours to destinations such as Gibraltar, Malta and Athens, sailing from Southampton. The forerunner of modern cruise holidays, these voyages were the first of their kind, and have led to P&O Cruises being recognised as the world's oldest cruise line.