* Winellie (Charles Darwin). Probably your best bet if your staying in town. Quite a bit of nice singletrack as well as fire trails. Some of the singletrack is currently off limits - please respect the closures and avoid these trails. They are listed on the DORC website.
* East Point - follow the paved cycle path along the coast from town. Look for the singletrack on the RHS just after the sweeping bend where the BBQ's are
* Lee Point - follow the paved cycle path from town around past nightcliff, cross rapid creek bridge and keep going past dripstone cliffs. Head towards the hospital and look for a dirt track on the left, cross a small bridge over a creek and just keep going, you will find the singeltrack (or maybe just get lost)
* Holmes Jungle - it's near the dump at Karama. Check a map to find out how top get there as it's a bit hard to explain. Quite a few trails there
* Howard Springs pine forrest - on the Howard Springs road on the LHS. If you have to ride from town it will take close to an hour to get there.
* Palmerston - nice singletrack along the escarpment on the LHS of Chung Way Terrace.
there are a few of the local ones. How long are you in Darwin for?