There is a bus from Ulaanbaatar to the park. It leaves from the south side of Peace Avenue, opposite of the big 'Narantul Hotel', 150 metres East of the junction with Ondor Gegeen Zanabazaryn Gudamj, which is the road that runs south from Gandan Khiid. The bus stand has a large "e-ticket.mn" sign on it. Buses leave at 11:00am and 16:00pm, and take 2 1/2 hours to get to Terelj village. Coming back, they leave Terelj village at the uncivilised hours of 08:00am and 19:00pm. The bus costs 2300 MNT one way (as of July 2009)
The road is paved all the way, fine for cars. Lots of UB residents come for the weekend, so you can probably find a ride back to UB pretty easily. Offer to help pay for petrol.
3000 MNT payable at the national park gate, 6km from the turnoff for the park road.
Trekking, Horse riding.
Ecotourism Ger Camp, (You can phone Bert for a pick up from the bus, or directions are to turn right after the UB2 hotel and wade across the river. After that turn right (east) along the track alongside the river that follows the electricity poles. When you reach pole numbered 40 turn 90 degrees right and it's in front of you.), ☎ 99734710. The affable Bert and his family run a friendly ger camp away from the main tourist area. He can arrange horse riding further into the park, including Gunjiin Sum and there's good hiking in the area. The food's great (including home made cheese).20 EUR Per person per night including all meals.
Other Tourist Ger Camps. There are numerous tourist Ger camps on the road as you approach Terelj village - some are closer to the road than others. Any of them can set you up with horse rental, otherwise you can just hike around the park.We paid 25,000 Tk for a 2-person Ger (no meals included). You might be able to bargain a bit, since there are a bunch of tourist camps and they're fairly indistinguishable..