Jankie is right, Jakarta is not ideal ... but for those desperate locals it's not too bad, a, just catch a taxi down to Ancol in North Jakarta and since January 2012 there is a small beach that's been built that's large enough to launch from about 200mx50m in size. There are "no swimming signs" as it drops off steeply, so don't swim, launch in 10-12kt wind during the dry season when it's blowing cross onshore NE just keep planing and have a good wash when you get home. There are some good 2-3km runs here inside the breakwater.
There are a two spots within 20-45 min of Jakarta on the coast, and thousand island may be possible but I've not yet to find an Island with a beach big enough to launch that's not overhung by trees.
(Bali on the other hand is very nice ).
1). Ancol, near Pantai Karnaval, (S 6.11 deg E 106.85 Deg) only 20-40min away on the toll road from downtown Jakarta.
, the sandy beach is too new for Google Maps satellite view it was widened in January 2012. check with wind forecast on http://www.windfinder.com/forecast/jaka ... jung_priok
In the far east of Ancol on the East of the Back Stage Club, slap bang in Jakarta about 500m west of the Ereveld Cemetry on Jalan Kawasan Wisata Ancol. Is a sandy beach about 200m long and 50m wide. Could be good from about lunchtime onward on the weekend (when traffic is lighter) if you feel a breeze in town. Pantai Karnaval is the penultimate eastern beach in Ancol, recently widened in January 2012, what forethought, who knows where the sand comes from. Generally it's so hot and sunny no-one is crazy enough to be out on the baking sand. I launched with a 19m2 kite one weekend on 23 June 2012 with 10-11 kts of wind, nice flat water behind a breakwater about 800m out. Great long 2-3km runs from here down to the Marina but with no-where else to land. Beach is wide enough to launch and land from, and nobody swimming in the water as you unlikely to be able see anywhere past your knees once in. Speak to the life guards before launching so they know what you are up to. Have a good wash after getting out is probably not a bad idea.
The sailboarders and dinghies tend to launch from two Western beaches in Ancol, 1. tiny little beach in front of the Mercure Inn, about the middle of Ancol below the cable car, sure death to any kite, and 2. far west, near the Marina, a little boat ramp, also too many lines, poles and people for launching kites.
Watch you don't get caught up in the jetties and rocks along the other parts of the shoreline, as there are only one or two places to launch and land in eastern Ancol beaches. Dodge the fishing/sailing boats taking locals for joy rides to watch the jelly fish. They seem friendly.
Another beach close to Jakarta is Tanjung Pasir. 6.01 Deg S, 106.68 Deg E
2). Tanjung Pasir, North West of the Airport past Kampung Melayu Barat? about 50-60 minutes drive from downtown Jakarta, past the airport, past two villages and some rice paddies and into a Naval village. Best to let the naval people know you are just coming to to kite a bit. The beach is wide enought to launch and land on the Eastern Side of Tanjung Pasir. Plenty of warungs selling BBQ fish. There is even toilets and shower near the beach to wash down before the trip home. You can see some of the islands from here. Watch for fish traps and anchor ropes.
3). Anyer. West Java. About 2hr 45min drive West is Anyer beach. 2hr on the toll road, and 45min of Kidney jarring bad roads outside the Krakatau Steel works. Not bad for a weekend., but very crowded with very small launch sites.
launch site is a walk south along a very narrow sometimes rocky beach only a few metres wide about 200m south of the Sol Marbella resort. The resort is not too bad to stay at, not fantastic value for money wise, but it's there. The beach launch on a cross shore breeze coming South West of the Sunda Straits is full of gusts and difficult coupled with the narrow beach about 10m wide and full of people in the small dumpy surf can be quite an exercise. There are probably better spots around if you can find them. Nice view of Anak Krakatau simmering on the horizon in the sunset though.
4). Some of the thousand Islands off the Coast of Jakarta might be good for a weekend kiting, provided you find one with enough sand to launch from. They are a 30-90min boat ride from the Ancol marina. home. You can see some of the islands from here. Watch for fish traps and anchor ropes. I've yet to find an island with a beach large enough and facing the right direction to launch from. Some stand up paddle potential on very small waves or inter island SUP paddling.