Gilligan's pedal powering a water wheel to water the Professor's garden. The spring dries up causing a fresh drinkable water crisis. Gilligan tries to stop whoevers is in the shower but on his way slips in the mud. Gilligan goes into the shower to clean off after Ginger leaves. When the Skipper arrives, Gilligan can't remember his news.
They start to ration water until they can find a news source of water. Skipper suggests not even using the word water so they won't think about it. All the castaways have to put their personal water supplies into a large community container. Skipper suggests using a diving rod to find their next source of water. Professor thinks it's ridiculous but the diving rod does find Thurston's personal ankle water flask. On their quest to find water Skipper suggests sucking on pebbles to build saliva until he chokes on them.
While Gilligan is watching the water supply Thurston and Ginger distract him while Lovey and Mary Ann steal water. Skipper catches the water thieves. To help Skipper, Gilligan makes a new diving rod. The Skipper promises that he won't be bad if the new diving rod hits water. The rod does hit water when it punctures a hole in the water supply draining all the water out.
Professor and Skipper start digging a well in hopes of finding water. Gilligan goes exploring because no one wants him around. The girls are making a tarp to catch the morning dew so they will have water. While the Howells do a rain dance. Gilligan writes a goodbye note and is interrupted by a frog jumping onto his paper. Gilligan follows the frog thinking it will lead him to a source of water. Mary Ann finds the note thinking that Gilligan went to do something desperate. While following the frog Gilligan falls into a deep cave full of fresh water. Skipper finds his buddy's hat and then falls into the hole too. The Howells find them tossing them some matches so they will be able to see. When they light ones there's a huge explosion because of the explosive natural gases. The explosion send Gilligan and Skipper up into a tree. Everyone celebrates over a mugful of nice fresh water.