Jungle Basin is a two-player map released by Blizzard. It features a protected in-base expansion with destructible rocks blocking a back door.
The map replaced Desert Oasis on the ladder in October 2010 and was subsequently used in the GSL and other tournaments. A version with additional gold bases appeared briefly on the EU server before the map was removed from the ladder on February 25, 2011.
Official Map Description
A central plateau with Xel'Naga Towers overlooks two main paths. Rocks protect a back door entrance to the enemy base. Additional resources are easy to get and easy to protect.
4 Warpgate play is common for Protoss because there are several excellent places to hide pylons. Specifically, by the backdoor rocks of an opponents base. 2 base play and all-ins are common due to the difficult defensibility of the expansions. The third is open to attack from multiple directions, while the fourth is a considerable distance from the main. Fast expansions are common, and a small ramp to your main makes it easy to defend both the main and expansion. the backdoor rocks in the expansion is a prime target, however, so care must be taken to defend it.
It is said to be extremely difficult for a Zerg to take a third expansion on this map.