Every year, during the leatherback nesting season (between October and March), leatherbacks come ashore to lay their eggs at night; up to 60 days later, the eggs hatch and the hatchlings start their race to the ocean. Black and olive ridley turtles also nest here, and portions of their nesting seasons overlap with the leatherback nesting season.  

There are seven different species of sea turtles in the world, and Playa Grande is regularly visited by the aforementioned three species. The leatherback turtle (baula in Spanish) can measure up to 130 – 190 cm (52 – 75 in) and weigh 250 – 500 kg (550 – 1100 lbs). Since leatherbacks exclusively feed on jellyfish species, it’s incredible to think they can grow this large on jellyfish alone! East Pacific leatherbacks migrate from as far south as the waters off Chile and Peru, where they forage in the cold upwellings of the Humboldt current, to tropical waters offshore nesting beaches where they lay their eggs, such as here in Guanacaste province.

The East Pacific Green turtle, also known as the black turtle (negra in Spanish), can measure approximately from 80-122 cm (32 – 48 inches) and weigh 65-204 kg (144 – 450 lbs). This turtle’s main diet is sea grasses and algae, and occasionally jellyfish. They travel along the coast of Central America and venture as far south as the Galápagos Islands.

The olive ridley (lora in Spanish) measures around 55 – 75 cm (22 – 30 inches) and weighs 36 – 45 kg (85 – 95 lbs). Olive ridleys are considered to be the most abundant sea turtles in the world, although the current global population is only 0.2% of the species’ historical abundance. Females often nest together in large aggregations, known as arribadas, which only occur on certain beaches, like the local Ostional. Scientists have recorded arribadas of up to 200,000 turtles at once. Olive ridleys forage along drift lines for crabs, jellyfish, clams, squid, snails and algae.

Playa Grande, Playa Ventanas and Playa Langosta, are all part of Las Baulas National Park (Parque Marino Nacional Las Baulas). The Park protects the last mass-nesting beach for the East Pacific leatherback turtle, a population designated as critically endangered by the International Union for Conservation of Nature (IUCN). Park Rangers, local guides, members of local communities, and researchers are working hard to save these turtles from extinction, as well to protect the local wildlife and flora.

Las Baulas National Park was created more than 20 years ago to protect the sea turtles and other ecosystems, including estuaries, wetlands, dry forests and the marine habitat extending 12 nautical miles offshore.

In the late 1980s, when The Leatherback Trust scientists began collecting standardized data on nesting turtles on Playa Grande and Playa Ventanas, they documented hundreds of turtles nesting on the beach each night during the nesting season. At that time, egg poachers had organized themselves in groups and divided up the beach to collect every last leatherback egg.  Unfortunately, the result was the loss of an entire generation of East Pacific leatherbacks.

The Leatherback Trust’s founders, Dr. Jim Spotila and Dr. Frank Paladino, worked with Mario Boza to create The Leatherback Trust to stop egg poaching at Playa Grande and Playa Ventanas and their support helped lead to the creation of Las Baulas National Park. Our organization’s scientists and volunteers continue to conduct monitoring activities at Playa Grande and Playa Ventanas, in communication with Park officials, and we are proud to say that today, there is virtually no poaching in Las Baulas National Park. Nevertheless, there are still other threats that compromise the survival of this species.

For every 1,000 hatchlings, only one sea turtle reaches adulthood. Climate change, pollution, nest disturbance, fishing and habitat loss are now the main threats to leatherbacks and other sea turtles. Increases in sand temperature due to climate change can kill hatchlings in the nest before they fully develop. Around 30°C the mortality starts to increase and by 33°C the mortality rate is close to 100%.

Plastic, lights, and water pollution can compromise the survival of sea turtles. Turtles can confuse plastic bags, straws, or utensils with food. Plastics can get stuck in their digestive systems or lodged in their nasal passageways, as our scientists have seen. Light pollution disorients the hatchlings trying to reach the ocean, making them more vulnerable to predation or dehydration; adult turtles trying to find their way to the beach to nest are also disoriented by coastal lighting. Water pollution from leaky septic tanks, agricultural runoff, oil spills, or even runoff of oily residue from streets can lead to respiratory inflammation, gastrointestinal ulceration, organ damage and reproductive failure.

Longline fisheries for tuna, swordfish, and mahi-mahi, as well as shrimp trawling present one of the most serious threats to sea turtles in the ocean. Although turtles are not targeted by these fisheries, they get stuck in weighted nets used by trawlers or entangled on the miles of lines with baited hooks set by longliners, becoming “bycatch” and often drowning when they are unable to surface for air. Costa Rica has taken action to improve fisheries practices, for example by phasing out bottom trawling for shrimp, but consumers must not only demand strong fishing regulations to protect sea turtles but also reduce demand for unsustainably captured fish.

Finally, habitat loss at nesting beaches can leave sea turtles with no place to nest. The shade beachfront trees produce can help cool nests, which impacts the gender of hatchlings. Loss of coastal vegetation also increases compaction of sand, preventing turtles from digging, and erosion, exposing nests to danger.

Las Baulas National Park, The Leatherback Trust and other organizations, companies, and neighbors are working together to help save sea turtles. How can you help? Here some tips from The Leatherback Trust’s Outreach Manager, Christian Díaz Chuquisengo:

1. Climate change: when using the A/C, use weatherstripping in windows and doors, to keep the cool air from escaping and reducing energy use. Turn off all your electronic appliances if you are leaving your home for several months. Replace incandescent light bulbs with LEDs and maximize use of natural light in your housing design. Ride your bike or walk when traveling short distances. Plant a tree near your house to increase shade and further reduce your electric bill. Support policies that reduce carbon emissions to mitigate climate change.

2. Pollution: if you live in a beachfront or oceanview building, use red filters or curtains at night in rooms facing the beach, to avoid disorienting turtles and other animals with artificial light. If you are visiting a hotel or renting a house, inform the owners about how to protect turtles from light pollution. Help us recover dark skies: fewer lights mean more stars!

Never forget the 3 Rs: Reduce, Reuse and Recycle. Tamarindo Development Association (ADI) organizes a recycling campaign the first Tuesday of each month. In Playa Grande, the National Park office collects aluminum beverage cans, plastic bottles, and glass. In other areas of Santa Cruz, the Municipality has a special truck named SE-PA-RE that collects recyclables.

Add another R by Refusing straws, bags, disposable utensils, and other single-use plastics. Join a local plastic reduction campaign or start your own! The No Straw Challenge (Sin Pajilla Por Favor in Spanish), created by 12 year-old Max Machum in Playa Grande, encourages businesses and individuals to reduce use of plastic straws by providing them only upon request or substituting with biodegradable straws. Many businesses in Tamarindo, Playa Grande, and Playa Flamingo are participating. Now it’s your turn!

3.  Nest disturbance: when you visit Las Baulas National Park beaches, remember there is a chance there could be a nest in the sand right under your feet! Don’t put sticks or umbrellas in the sand above the high tide line. Bring a towel and find a place to sit between the ocean and the high tide line. Leave your dogs and other pets at home. Dogs can dig up the nests or dig near them, exposing the eggs to predators or interfering with hatchling development. If you visit unprotected nesting beaches outside the Park with your dog, use a leash.

4. Fishing: support artisanal fishermen that use responsible fishing methods, such as pole fishing, trolling, or handlining. Educate your friends about sustainable fishing practices. Beware the vague term “line-caught fish”, which is often used to make longline fishing sound better. Eat low on the food chain and buy seafood from sellers that are committed to marine sustainability, respect fishing bans, or buy certified seafood. When you visit a restaurant, ask your waiter information about seafood and encourage businesses to buy from sustainable distributors or local artisanal fishermen using responsible fishing methods.

5. Habitat loss: if you are building or buying a house, make sure it is set back from the beach. Don’t buy properties within parks and adhere to restrictions on construction and resource use in parks, protected areas, and buffer zones. Minimize water use in landscaping. Plant native trees for shade to provide habitat for local species, prevent erosion, and minimize light and sound pollution on the beach.

When each of us begins to take action to protect the environment, the changes add up to benefit all living things, including critically endangered East Pacific leatherbacks. Let’s all remember: their future is in our hands.

This article originally appeared on National Geographic’s Ocean Views blog