THEME PARK is an acronym for Training Habitat Encouraging Maximum Effort. Progress, Achievement, Reward and Know-how and is shown in the anime as the location where HIKING trips take place.
A THEME PARK is a training area where numerous contraptions have been set up to create extremely dangerous situations. Depending on where the THEME PARK is created these traps can range from violent piranhas in the middle of rivers, snakes, leeches, and variety of other animals to put training shinobi in harms way. However it is possible for other man-made contraptions to be present as well to further invoke danger when triggered.