"Big Water" is a Land Before Time term for the ocean. It is the place where Mo and Elsie and some swimming sharpteeth live. The water is salty. The island where the gang encountered Chomper in the 5th movie which is surrounded by this. It is also near the Big Water, as of looking for Littlefoot and his friends that the Great Valley adults had found a spot with plenty of fresh water and green food for the herd to stay till the Great Valley regrew and they were able to return.
The ocean once again returned in the 9th movie when they helped Mo to return to the Big Water, though it seems to be not the same place as part of the 5th movie that took place.
The Big Water appeared in the 5th movie of the Land Before Time series called 'The Mysterious Island' where they meet and encountered Chomper, a Sharptooth from the second film, 'The Great Egg Adventure' at a mysterious island which is surrounded by water. It was near the ocean where the adults of the Great Valley who are looking for Littlefoot and his friends (Cera, Petrie, Ducky, and Spike) had found a good spot with plenty of fresh water and green foods for the herds to stay until the Great Valley can grow more green food and they finally return to the valley (meaning the Great Valley families).
The Big Water returned once again in the ninth film, "Journey to Big Water" which the producer and director of the film said that the ocean will not be taking place at the part of the 5th movie, where Littlefoot decided to help Mo return to the Big Water after the rain had flushed down on the Great Valley. Mo stated that he will return in a TV episode of the Land Before Time series called "The Missing Fast Water Adventure" where he helped Littlefoot and his friends remove rocks after two earthshakes had happened in it as he wanted to return back to the ocean and he did it.
SongBig Water as a location in the Land Before Time series is known to be as a song which Littlefoot and his friends (Cera, Ducky, Spike, and Petrie) sang it for the first time in the film "The Mysterious Island" and then with Mo's help, he and the kids sang it in Journey to Big Water and in the TV episode, "The Missing Fast Water Adventure" that Chomper and Ruby sang it with Mo, Petrie, Cera, Littlefoot, Spike, and Ducky without a few parts of the song in the two films, a different musical tone and the music is the same one to the two films. The TV episode's song is joined by three more in later episodes (The Spooky Nighttime Adventure, The Big Longneck Test, and The Hermit of Black Rock) as the strong resemblance to Big Water.
The songs were in the TV series, resembling to Big Water are:
The episode of The Land Before Time, 'The Missing Fast Water Adventure' is the fourteenth episode in the television show and is listed between the thirteenth one, 'The Lonely Journey' and the next episode with the resembling song including quite a scary one because of the sleep stories and Hidden Runner is 'The Spooky Nighttime Adventure' which this is the only one to be very spooky.