Passenger boats with powerful outboard motors ply the Rio San Juan, from San Carlos all the way to San Juan de Nicaragua on the Caribbean Sea. Boats stop as needed at various ranchos, but the most important regular stops are Boca de Sabalos and El Castillo, which are about 1 1/2 and 2 hrs down river from San Carlos. Like its name implies, Boca de Sabalos is at the mouth of one of the many tributaries of the Rio San Juan. It's a busy rustic town with a fish statue. El Castillo is on the edge of the Biosphere Reserve and has the distinction of being the defender of Granada since the 17th century.
Tickets are purchased or reserved in a variety of ways. In San Carlos, tickets are normally purchased at the termal building window. In Sabalos or El Castillo, the hotel can make a reservation, and then payment in made to the conductor during transit. Price is $3- normally; however, it the regular schedule fills up and an additional boat is required out of San Juan, price my inflate to $4-. If you are not able to get tickets in time for a regularly scheduled boat, and it's not too late in the day, be patient. See who's standing around and expect to fill another boat. Private boats are also available at a much higher price. Baggage will cost extra, and are stored on the roof of some boats. There are slow and fast boats, and in our case, the extra schedule fast boat that cost us $4- caught up with the slow $3- boat at Sabalos, so we stopped at the dock there to transfer the for the remaining 30 minutes of the ride to El Castillo.
There are also less frequent boats from San Carlos that stop at El Castillo for the trip all the way to San Juan de Nicaragua on the Caribbean Sea. The Nicaraguan army often uses the river transport to move it's personnel along the river. The river is not far from the border of Costa Rica and there is some tension over ownership of the waterway.
Around San Carlos, but more likely around El Castillo, one can hire a canoe with boatman to personally show you a tributary of the San Juan river. In our case, we were tired of the motorized boat transport, the loud and vibrating motor of which makes wildlife watching and photography difficult. So, I hired a strong Nicaraguan young man named Daryl to paddle my wife and I along the Rio San Juan and up a quiet tributary for some bird watching. Originally, I was going to get the exercise of paddling myself, since I do have some sportsman like strength still, but the boatman paddled like an Olympian. I had thought that he and I could push my tiny wife upriver a bit. Perhaps not surprisingly, he knew so exactly how to position the canoe to take advantage of downstream currents in the rapids, and quiet upstream eddies in what would otherwise be very hard paddling. Plus, the boatman could identify and spot wildlife very well. We saw many birds and monkeys on our trip. So mostly, I ended up setting the paddle aside and stuck to the enjoyment of my big lens photography. The boats are not normally dugout canoes in the technical sense. While there are plenty of those on the river, the typical boatman like we hired has a fiberglass canoe which is safer and more comfortable.
To find our boatman, go to Tour Canoas Basilicus in El Castillo. It's easy to find him (I forgot his name, and may not have it correct here) because his family has a restaurant on the waterside, about halfway between the dock and Victoria Hotel. The restaurant is OK too. See photo.
Guidebooks for transport to Solentiname Islands were especially vague, and so we probably ended up paying more than we had to for service that wasn't exactly what we wanted. But, we did have good service overall, and I recommend considering Jose Pineda, who is also friends with folks in El Castillo, and may work out a combined deal for a larger party if you want. In our case, we learned rather late about the cheap municipal service to the islands, thinking that private boat was the only option. From our hotel in El Castillo, we negotiated a package of cheap cabin (see my tip on this) for $30 per day, and two days worth of private motorized transport for $200-. Jose's boat has a powerful motor, and he can navigate safely across sometimes choppy Lake Nicaragua. In our trip out to the islands, we had tropical rains and significant swells that he couldn't simply power through. We didn't vomit or anything, but the smaller boat was pushed about a bit, and we felt value in wearing the life preservers. On the way back to San Carlos, the water was as smooth as glass, and Jose's fast boat was a blast!
In addition, his son took us around to some other islands during another day (see other tips for more images). The only disappointment was that during the day of visiting the other island, the power and vibration of the outboard motor was really too much. Even idling, the huge outboard rattled the boat, making big zoom photography very difficult, as trolled through the water too fast. I later recommended to Jose that he get an auxiliary electric trolling motor for nature watching near the smaller islands. In any case, I would have preferred to have a canoe, because the outboard was simply not able to hug close to shore. Nevertheless, this private service was much more pleasant than joining a larger group of tourists, a more common event in these waters. This was overall a worthwhile excursion, and one of the highlights of our trip to Nicaragua.
I recommend that when in San Carlos at the dock, check out the schedule for the municipal service, which is very cheap. If it fits your schedule, contact Jose for the cabin, and then plan to work out a deal at the island for either motorized or canoe transport to the other islands. Although the Solentiname Islands are at least an hour from San Carlos, the archipelago itself is clustered close enough for canoe or kayak on a calm day.
Prices vary of course, but the 12 seater twin prop airplane service from Managua to San Carlos is very good and reasonably priced. We paid $75 per person for an hour long flight during high season. Website doesn't work very well, but there are regular flights 5 days a week for which early reservations are highly recommended. TripAdvisor warnings about credit card fraud are unfounded in my opinion. Like most any Nicaraguan company, the corporate level telephone and internet service is crummy, but the quality of personnel is good. The Managua domestic airport is right next to the relatively small international airport, so immediate transfer is not outside the realm of possibility. But, we found that contacting La Costena from abroad was very difficult, even though the website appears impressive at first inspection. The flight south has the potential of great views of Lake Nicaragua. The San Carlos airport is a heavily eroded, nearly unpaved, strip of asphalt on a hill above the city. Touch down was not too bad in spite of primitive air strip conditions. All tourists must present passports in San Carlos. I have more images of this flight to San Carlos elsewhere in this guidebook.
We flew south, but we were willing to go on the cheap and take the six hour bus back to Managua. The bus is slower than the plane, but a lot faster than the ferry. At $6- per person, it was a good deal too. The buses are comfortable enough, being older Marco Polo style buses common to the better Latin American bus companies. Seats were clean, and headrest linen was fresh for our ride.
There is a new highway from Managua through to San Carlos that is not yet well advertised in the guidebooks, so don't be persuaded to think this is a rough and challenging ride. It's not. The most difficult part for tourists might be the frequent stops, which adds as much as an hour and a half to the trip. But, the landscape is pleasant enough, traversing the cattle ranch region of Nicaragua most tourists don't bother to visit. Watching the cowboys, with their hats and ropes, board the bus for a stretch is good people watching. I saw a saddle maker in a pueblo along the way.
Check the schedule at the San Carlos bus terminal, but there are at least four buses daily, some being faster than others. Not much need to purchase the ticket in advance, except to secure a good seat. We tipped the conductor to handle our baggage, but there was otherwise no additional charge for storage in the secure and weather tight lower cargo hold of the bus. Contrary to guidebook impression, the San Carlos bus station is neither gritty nor dangerous.