The tourist infrastructure on this side of Volcán Barú is far less developed than it is around Boquete . Guiding operations are more casual, and several of the guides I’ve recommended in the past are no longer in the area.
The safest bet is to make arrangements through your hotel, particularly if you’re staying at Los Quetzales Lodge and Spa or Hostal Cielito Sur in Cerro Punta ; these two places should know the best available guides. Another option is to arrange a package with an outside tour operator that employs naturalist guides, such as Ancon Expeditions.
Summiting Volcán Barú  is the big physical challenge around here, but there are plenty of other high-adrenaline possibilities, as well as gentler options.
Hostal Cielito Sur (tel./fax 771-2038, cell 6602-3008, www.cielitosur.com ) in Cerro Punta rents mountain bikes for US$5 an hour or US$20 a day. Hotel Bambito (tel. 771-4373 or 771-4374, www.hotelbambito.com ) rents mountain bikes for US$5 an hour and horses for US$8 an hour.
Los Quetzales Lodge and Spa (tel. 771-2182 or 771-2291, cell 671-2182, www.losquetzales.com ) arranges birding tours, including a vehicle with driver and guide, for US$60 for a half day, US$90 for a full day. Hostal Cielito Sur (tel./fax 771-2038, cell 6602-3086, www.cielitosur.com ) arranges birding tours for US$40–60 for a half day, US$70–100 for a full day, not including transportation.
A number of hotels and guides offer white-water rafting trips. Note that all of them contract out to rafting companies in Boquete , on the east side of Barú, so find out if the tour planner is charging you a premium just to book the trip for you. You might do better to contact the company directly.
The companies can usually pick rafters up and take them to rivers on either side of the mountain. Organized guide services and outfitters have been slow to take hold on this side of the mountain. Going through your hotel is the best bet for now.