Oreburgh Gate is the first actual cave that you'll traverse through in the Nintendo DS video games Pokémon Diamond and Pearl and Pokémon Platinum. In all, there are a total of eight different Pokémon species in the dungeon, which consists of 2 different levels. The top level has two different trainers who would like to battle you, while the bottom level doesn't have any. If you're trying to collect many Pokémon, then you'd probably want to go on the second level, seeing as many different species of Pokémon are there, including all the species from the first level.
Right when you enter the cave, you'll be greeted by a hiker who will give you the very helpful HM06 (Rock Smash), though to use it you'll first have to fight and defeat the first Gym Leader (Gym Leader Roark). On the bottom level you'll find five different items, including a TM70 (Flash), which is sure to help you in future dungeons such as the Wayward Cave where there is no light at all. Other items include Stardust, TM31 (Brick Break), TM01 (Focus Punch), and Earth Plate, which raises the power of ground type moves.
On the second stage, to get to the other side of the stream, you'll have to have a bicycle, the coal badge, surf and rock smash. On the other side you find two of the aforementioned items (focus punch and earth plate).
On the first floor, the exit to the other side will lead to Oreburgh City.
List of Pokémon