The island where Amy and Henry at has a dense forest and a wide land area. After Henry went into it, he immediately noticed the change in temperature. The air is much cooler so he mentally noted to relocate Amy later.
He did not have to look further deep into the forest for he shortly found a stream similar to the mini island in the resort but much smaller. Just about three feet wide and a foot deep. Henry quickly ran towards the stream and used the banana chips wrapper that they kept to bring water to Amy.
Good thing the water is clear and looked clean, and even if it is not, he had no other choice but to use it given their situation. He slowly scoop the water and ran back to his wife as fast as he could.
