The Oceans Surrounding San Cristóbal Island / Chatham Island
- The Persaud Catalog
- Aug 20
- 5 min read
Updated: Aug 20
In this article, we will discuss the oceans of San Cristobal Island / Chatham Island. San Cristobal Island is a part of the Galapagos Islands Archipelago, located in the southern Pacific Ocean.
Out of all the Galapagos islands, San Cristóbal Island is the farthest east. San Cristobal Island is located approximately 501.75 nautical miles (577.403588 miles or 929.241 kilometers) off the central coast of Ecuador. Though San Cristobal Island is not the main Galapagos island, it is one of two islands with an airport. It is the fifth largest of the 127 Galapagos islands.
The island has a very low population, with only about 6,000 inhabitants. The island is extremely biodiverse, & has vibrant marine ecosystems that are directly connected with the towns around them. Many consider the sea lions that live on the beaches, walkways, & park benches to be locals. The majority of the beaches, as well as coastal walkways on the island, have these marine mammals on them.
A Sea Lion barking along a beach on San Cristobal Island, Galapagos Archipelago, Ecuador. Credit to the Galapagos
Aside from the Sea Lions, San Cristobal Island has a variety of other interesting marine species to offer. These creatures range from reef sharks to exotic & colourful fish. One of the most well-known places to find these reef sharks is Kicker Rock. Kicker Rock is located off the coast of the northwestern portion of the island. It is the remnants of a volcanic eruption. The area is most well-known for its magnificent coral reefs that have a large population of Galapagos sharks. Since this group of rocks is so far away from San Cristobal Island, it is only accessible by boat.
In this article, we will discuss the Salinity, Tides, Marine Geography, & Depth of the waters surrounding the island, the most prominent marine ecosystems of the island, the marine flora & fauna of the island, & how oceanic rising temperatures, as well as oceanic acidification, are affecting the island. With that being said, let us delve into the oceans surrounding San Cristobal Island.
The Salinity, Tides, Temperatures, Marine Geography, & Depth Of The Oceans Surrounding San Cristobal Island
The Salinity around San Cristobal Island is approximately 33.5 parts per thousand. For every 1000 grams of water, there will be a certain number of grams that are pure salt. This is how salinity or saline level is measured. There are also no ongoing factors that would lead to the salinity level being altered.
The tidal charts around San Cristobal Island are found on a plethora of websites, a few of which are: https://www.tide-forecast.com, https://www.tideschart.com, & https://www.seatemperatu.re. Generally speaking, the tides rarely get over 6 feet tall.
The oceanic temperatures can be found on similar websites, such as: https://www.seatemperature.org, https://seatemperature.net, https://seatemperatures.net, https://www.tide-forecast.com, & finally https://seatemperature.info. The average yearly oceanic temperature is currently 24.7° Celsius (76.46° Fahrenheit). Using this average, it is recommended that swimmers wear a 3 millimeter full suit, or a 2 millimeter short suit.
The area is not known to have high riptide, & is perfectly safe for swimming, snorkelling, & scuba diving. There is very little oceanic pollution, & it is considered to be safe for humans to swim in the ocean. In the oceanic areas closer to the coast, the water is known to get at least 130 feet deep. There are no known oceanic canyons near the island, nor are there any seamounts.
The Galapagos Islands have several Marine Protected Areas, which are known as The Galapagos National Park Marine Reserve, The Galapagos Marine Reserve, & the Galapagos Biosphere Reserve. For the beautiful coral reefs & expansive forests, San Cristobal Island is extremely popular for Eco-Tourists. The majority of these Eco-Tourists will do hiking, wildlife observation, snorkelling, & scuba diving. Some of the best beaches for wildlife watchers, swimmers, & snorkelers, are considered to be: La Loberia, Puerto Chino Beach, Cerro Brujo, Playa Mann, Punta Pitt, Playa Punta Carola, Playa Baquerzio, Playa De Oro, Puerto Grande, Playa El Manglecito, Los Marinos, & Muelle Tijeretas.
The Most Prominent Marine Ecosystems Of San Cristobal Island
Ecosystem Type No. 1: Fringing Coral Reef
Fringing Coral Reefs are the most common, as well as well best-known ecosystem. Around the island, the coral reefs are of the fringing type; hence the name fringing coral reefs. These ecosystems are the most biodiverse, & are extremely important to the island. Coral reefs are used as shelter, spawning grounds, breeding grounds, & hunting grounds. Around San Cristobal Island, there are both shallow & deep-sea coral reefs. These coral reefs range from being 5 to 1,500 feet (1.52 to 457.2 meters) deep. Not only do these coral reefs provide a haven for marine life, but they also act as a natural cushion to the waves & storms around the island.
Ecosystem Type No. 2: Coastal Mangrove Forests
Towards the southern end of San Cristobal Island, there are multiple areas of mangrove forests. These mangrove forests are extremely important to the island's ecosystem diversity, as they house many different species, a few of which are endemic to the Galapagos Islands.
On San Cristobal Island, there are an estimated 4 species of mangrove tree: Laguncularia Racemosa (White Mangrove), Avicennia Germinans (Black Mangrove), Rhizophora Mangle (Red Mangrove), & Conocarpus erectus (Buttonwood Mangrove). These mangroves have incredibly deep waters, so much so that rays can navigate them regularly. These mangrove forests serve not only as a refuge for marine life, but also as a natural habitat for Waterfowl.
The Documented Marine Flora Of San Cristobal Island
Being in the Galapagos Islands, the island has a big variety of marine flora as well as fauna. As said in the subsection titled “Ecosystem Type No. 2: Coastal Mangrove Forests”, the primary mangrove species are as follows: Laguncularia Racemosa (White Mangrove), Avicennia Germinans (Black Mangrove), Rhizophora Mangle (Red Mangrove), & Conocarpus erectus (Buttonwood Mangrove).
Unfortunately, as for oceanic flora that grows directly in the ocean, there is little to no data. There are no current issues with invasive marine plant species, invasive parasites, or invasive diseases.
The Documented Marine Fauna of San Cristobal Island
Marine Fauna around San Cristobal Island is plentiful & very diverse, ranging from colourful tropical fish, to fur seals who are practically citizens. Since San Cristobal Island has both shallow & deep-sea coral reefs, the island provides a very rich habitat. As of 2025, there are at least 5 endemic marine animals, discounting waterfowl.
How Rising Oceanic Temperatures Are Affecting San Cristobal Island
Unfortunately, the coral reefs around San Cristobal Island are incredibly easily affected by rising ocean temperatures. During events in which the water temperature spikes, the coral will become stressed out, & will eventually bleach. Once the coral becomes stressed, it is difficult for it to recover. With intervention, Coral can heal within the first few weeks of bleaching. Once it reclaims its food source & zooxanthellae, it will slowly begin to heal. There have been a few mass-scale bleaching events, namely the 1990s & 2010s. As ocean temperatures rise, more of these events could occur, & diminish the coral population even more.
Directories / Credits
Citation No. 1: “Wetsuit thickness and temperature guide, Written by Mark Evans, & Published on April 24th, 2023, at 3:05 PM. Published By Scuba Divers Magazine. Retrieval Date: December 12th, 2023.
Citation No. 2: “5 BEST BEACHES INSAN CRISTOBAL, GALÁPAGOS”, Written by Unknown & Published On October 29th, 2022. Published By The Portuguese Traveler. Retrieval Date: December 13th, 2023.
Citation No. 3: “Creativity in Science: Studying Mangroves in Galapagos” Written by Isabel Grijalva and Nicolálas Moity & Published on March 4th, 2021. Published by the Charles Darwin Foundation. Retrieval Date: December 13th, 2023.
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