After a failed attempt at hunting a pig, Jack returns to the place where Ralph and Simon have been working on the shelters. Jack is frustrated but optimistic that he will eventually get a pig. Ralph is frustrated because the hut they've most recently been working on has collapsed. He's also frustrated because most of the other boys work for a while and then quit to go swimming or play. Even the majority of the hunters left Jack to do the same.
Ralph and Jack are the two leaders of the camp. Up to this point, they have not clashed in a significant way, but their priorities are beginning to diverge. Ralph is clearly more ethical, responsible, and reasonable. Ralph is upset that Jack is more interested in killing the pig than he is in being rescued (keeping the fire going).
After arguing about these priorities (shelter, fire, meat), they both walk to the water. Ralph feels the increasing burden to keep the fire going and to build the shelters. Jack is beginning to become less civilized, focusing more on killing, not just for meat but for the sport of it. Therefore, having different priorities for their very survival, they are like two different continents with different languages. They can not communicate because they disagree on how things should be prioritized.
Their disagreements are burgeoning into hate but they still feel the bond of being stuck together, dependent upon each other for survival. It was this necessary camaraderie that brought them back together:
All the warm salt water of the bathing pool and the shouting and splashing and laughing were only just sufﬁcient to bring them together again.