There are plenty of beautiful islands and dive spots to explore. Nearby islands include Isla Cebaco, known for clear waters and good coral. But the biggest draw is Parque Nacional Coiba , at the heart of which is the astonishing Isla de Coiba, about a 1.5-hour trip away by fast boat.
Given the distance and how amazing Coiba is, those with the time and money should consider staying overnight on the island. You may not have to go nearly that far to encounter spectacular sea life. On my first visit, I watched as an enormous humpback whale surfaced near my boat between Santa Catalina  and Isla Cebaco .
Some of the hotels and surf camps offer trips to the islands, usually on pretty basic pangas. These should be fine for trips to nearby islands, but I don’t recommend them for trips on the open ocean. For trips to Coiba and other distant destinations, stick with substantial boats that have life preservers, an emergency radio, and, preferably, a spare motor. The seas can quickly turn rough out here, and the ride to Coiba is bumpy year-round.
There are now two dive operators in Santa Catalina. They’re virtually across the street from each other, near the end of the main road just before the beach, making it easy to do comparison-shopping. Both seem good and run professional operations.
Both offer dives on 25-foot boats at a number of spots close to Santa Catalina and around Parque Nacional Coiba , which is about a 90-minute boat ride away. The cheapest scuba trips at either place are a two-tank dive at nearby spots (US$55 pp). A two-tank trip to Parque Nacional Coiba starts at US$95. Rates include guide, tanks, and weights. Add US$15 to the prices to rent full diving gear.
Both dive operators also accommodate snorkelers and those interested in exploring Isla Coiba by land. Be sure to ask for the itinerary of these trips, as the area around the ranger station is a popular first stop but only a taste of what the island and its waters have to offer. A good introduction to the area would also include a visit to the Bahía Damas  area, on the east side of the island.
Note that the entrance fee for Parque Nacional Coiba is US$20 per person, payable at the ranger station on Isla Coiba.
Besides Coiba and the local area, Coiba Dive Center (tel. 938-0007 or 202-9214, www.coibadivecenter.com  or www.scuba-charters.com ) makes trips all over the Golfo de Chiriquí , including Islas Secas, Islas Ladrones , and Isla Montuosa . There’s a two-diver minimum on all dive trips.
A full-day Coiba snorkeling trip costs US$50 pp, but consider the US$60 pp Coiba tour, which includes a half day of snorkeling and a half day on the island, including a tour of what’s left of the penal colony. All prices include gear and transportation. PADI certification courses start at US$130 for a one-day, one-dive Discover Scuba course. Other courses range from a scuba refresher up to PADI Advanced Open Water.
Scuba Coiba (tel. 202-2172, www.scubacoiba.com ) was the first land-based scuba operation in Santa Catalina , having opened in 2003. They speak English, Spanish, and German here. Besides its day trips to local spots and Parque Nacional Coiba , it also offers multiday Coiba trips, with overnight stays on Isla Coiba.
There’s a two-diver minimum on most of the trips, but singles can arrange a two-tank dive close to Santa Catalina for US$75. PADI certification courses start with a one-day, one-tank Discover Scuba courses around Santa Catalina (US$70) or Coiba (US$110). Other courses range from a scuba “tune up” to Advanced Open Water.
Fluid Adventures (cell phone 6560-6558, http://fluidadventurespanama.com ) offers a whole range of water-based adventures. These include sea-kayak trips around Santa Catalina (US$40–50 pp) and Isla Coiba (US$105 pp, four-person minimum, including boat transport to Coiba but not the park entrance fee). Overnight and multiday kayak trips are available. Single (US$35/day) and double (US$55/day) kayaks are available to rent, as are surfboards. They also offer surf and yoga classes. Their office is toward the end of the main road, next to Scuba Coiba.