The dives and cracks have hidden treasure which it can only be accessed if you feed your chocobo a dead pepper. There are 2 cracks in the Forgotten Continent(one of them has Freya's Ultimate Weapon called Dragon's Hair), the center of the ocean where that portal would transport you to Terra has Zidane's Ultima Weapon(disk 4 only). There are more spots but I can't remember them at the moment