Depending on the season, it is possible to see the leatherback, hawksbill or green turtles coming ashore to lay eggs. Unfortunately, all of which are endangered. Although mother turtles can lay about 100 eggs at a time, only 1 in 1000 baby turtles will survive through adulthood.
I was in Parismina early in the leatherback season. So I only walked the beach at night with other volunteers. Once we spotted a turtle, we would measure and tag the turtle. Then relocate the eggs closer to the village so that they can be safe from poachers, who sell the eggs for money. You can help save the turtles by patrolling on the beach and working in the hatchery. If you're planning to help, try to stay for a week (if not at least 4 days), as there are various training on the first 3 nights.
It is certainly an unforgettable experience. Seeing the turtle laying eggs is just incredible...I can't describe with words, you'll have to see it for yourself! (No camera is allowed during the night patrol as the flash will distract the turtles.)
You can hire a boat for sportfishing. In fact, many tourists come to this area for sportfishing. And this is the village's main source of income. I'm not interested in this activity but I heard that it is quite expensive.
You can also fish along the beach with other locals. They use only a fishing line. The best time is early in the morning or late in the afternoon. You can find yourself a delicious meal!
I joined a full-day wildlife watching boat tour in Parismina. The boat went along the scenic Rio Parismina and the canals of Tortuguero. There were only 3 of us in a small boat. This is a great advantage compare to going on a tour in a large boat. Smaller boats can go to places where large boats can't, meaning you can see more. The guide, Rick, was very experienced, enthusiastic, and knowledgable about wildlife. We saw toucans, caimans, sloths, blue-jean dart frogs, basilisk lizards, and many other types of birds.
There is an airstrip in Parismina. It'll be very costly to fly here by charter flight, unless you have your own plane.
There is no road to Parismina. You can take a 15-min boat ride from Cano Blanco, a small village east of Siquirres for 1000 colones.
Another way is from Tortuguero or Moin via a canal parallel to the Caribbean Sea. I'm not sure how much this trip costs.