Sunken Volcanoes: Hawaii’s Hidden Gems

Hawaii’s volcanic landscape isn’t limited to what you see above the waves. Submerged beneath the turquoise waters are the remnants of ancient volcanoes, geological wonders teeming with unique life. These sunken giants tell a story of Hawaii’s fiery birth and offer divers and researchers alike a glimpse into a world shaped by intense geological forces and adapted remarkably by marine ecosystems. This article dives into the fascinating world of these underwater volcanoes, exploring specific locales, what makes them special, and how you can (perhaps!) experience them.

The Hawaiian Hotspot’s Legacy: A Volcanic Family

The Hawaiian Islands are the youngest expressions of a long-lived volcanic hotspot. This hotspot, a plume of unusually hot magma deep within the Earth’s mantle, has been relentlessly punching through the Pacific Plate for millions of years. As the plate slowly drifts northwest, the hotspot continuously creates new volcanoes, leaving behind a trail of islands and seamounts like a geological breadcrumb trail. Many of these earlier volcanoes, once towering above the waves, have since eroded and subsided, becoming the submerged landscapes we’re exploring today. The Hawaiian-Emperor Seamount Chain, for example, stretches for thousands of miles and includes countless submerged volcanoes, reflecting the full history of the hotspot. The rate of plate movement contributes to the chain’s formation by moving the plate away from the hotspot’s consistent location for each island (Hawaii Undersea Research Laboratory, SOEST). The active volcanoes of Kilauea and Mauna Loa on the Big Island are just the current chapters in this ongoing story.

L&333;&699;ihi Seamount: A Volcano in the Making

Perhaps the most exciting submerged volcano in Hawaii is L&333;&699;ihi Seamount. Located about 22 miles off the southeast coast of the Big Island, L&333;&699;ihi is an active submarine volcano slowly but surely building itself towards the surface. It currently sits about 3,000 feet below sea level. What makes L&333;&699;ihi so interesting? It’s a living laboratory for scientists. Because it’s actively erupting, researchers can study firsthand the processes that create and shape volcanic islands. This includes the formation of new vents, the composition of lava flows, and the emergence of unique ecosystems adapted to the extreme conditions around hydrothermal vents. Hydrothermal vents, nicknamed “vent fluid plumes”, are unique to L&333;&699;ihi seamount because they support chemosynthetic bacteria, a type of organisms that can thrive on chemicals like sulfur instead of sunlight (Hawaii Undersea Research Laboratory, SOEST).

Unfortunately, diving L&333;&699;ihi yourself is not an easy or recommended option for recreational divers. The depth and the active volcanic activity make it extremely dangerous. However, the Hawaii Undersea Research Laboratory (HURL) conducts regular research expeditions to L&333;&699;ihi, often using manned submersibles. While you may not be able to join these expeditions directly, HURL often shares its findings and videos with the public, offering a virtual glimpse into this fascinating underwater world. Keep an eye on their website and social media for updates.

The Penguin Banks: A Sunken Reef in the Making

West of Molokai lies the Penguin Banks, the largest submerged reef ecosystem in the Hawaiian Islands. While not a classic sunken volcano in the same sense as L&333;&699;ihi, the Penguin Banks represent a feature formed on the flanks of a large extinct volcano from West Molokai. This shallow, submerged platform is a haven for marine life, with vibrant coral reefs, abundant fish populations, and frequent visits from Hawaiian monk seals and green sea turtles. The average depth is only around 30-100 feet, making it much more accessible to scuba divers and snorkelers compared to deeper submerged volcanoes.

While diving on the Penguin Banks is possible, it’s not as readily accessible as popular dive sites closer to shore. You’ll likely need to charter a boat from Molokai or Oahu to reach the area. Be sure to choose a reputable operator with experience diving in that location. The conditions can vary, and strong currents are sometimes present. You’ll want to ensure the captain and crew are knowledgeable about the area and prioritize safety. Expect to pay around $150-$300 per person for a full-day dive trip. Confirm costs and details directly with the charter company. While the Penguin Banks are not actively volcanic, the geological forces that shaped the surrounding islands played a crucial role in the formation of this unique underwater ecosystem.

Diamond Head Crater: An Explosive Past

Everyone recognizes Diamond Head (L&275;&699;ahi), the iconic volcanic tuff cone that guards the eastern edge of Waikiki. But did you know that much of Diamond Head’s story is actually underwater? The crater itself was formed by a single, short-lived explosive eruption that occurred perhaps 400,000 to 500,000 years ago. The eruption rose through an existing coral reef, incorporating reef fragments and sediments into the volcanic ash and creating the distinctive mix of materials that make up the cone. While the above-water portion of Diamond Head is impressive, consider the underwater slopes that extend outwards from the base of the cone. These underwater slopes are likely covered in volcanic debris and potentially some reef structures that predated the eruption. While diving directly around the base of Diamond Head isn’t a popular activity due to the surge from the waves and the proximity to boat traffic, nearby dive sites offer a glimpse into the geological history of the area.

Exploring the Submerged Coastline of Oahu

Oahu’s coastline is riddled with interesting formations that tell a story of rising and falling sea levels, and volcanic activity. Consider the dive sites along the south shore of Oahu, like those near Honolulu. Many of these sites feature lava tubes, arches, and other underwater formations that were once part of the exposed coastline. These geological features are now home to a wide array of marine life, creating fascinating dive and snorkeling opportunities. For example, the Corsair Airplane Wreck near Honolulu has also been colonized by many types of coral and reef fish over the years (Hawaii Department of Land and Natural Resources). These dive sites are often easily accessible from shore or a short boat ride, making them very popular among tourists and locals alike. The cost for a typical two tank boat dive on Oahu ranges from $120 – $180. Confirm costs and details directly with the dive operator. As you explore these sites, remember that you’re seeing a landscape shaped by volcanic activity and changing ocean levels – geological processes constantly interacting to create the Hawaii we know today.

Molokini Crater: A Partially Submerged Volcanic Cinder Cone

Off the coast of Maui, you’ll find Molokini Crater, a partially submerged volcanic cinder cone. This unique formation attracts snorkelers and divers from all over the world. Molokini’s crescent shape provides sheltered waters with outstanding visibility, making it an ideal spot to observe a vibrant coral reef ecosystem. Molokini is thought to have formed over 230,000 years ago. Before becoming a sunken volcano, the volcano erupted and formed as a tuff cone. Then, due to erosion over time, one wall of the volcano broke down, which has contributed to the half-moon shape that visitors see today (Maui Guide). While the volcano that created Molokini is long extinct, its legacy lives on in the stunning underwater landscape and its diverse marine life. Boat tours to Molokini run from around $100-$200 per person, depending on the company and the offerings. These tours typically include snorkeling gear, lunch, and guidance from experienced crew members. Look for tour operators dedicated to responsible tourism practices to help preserve Molokini’s unique environment.

Maui’s Back Wall: Diving the Deep

For experienced divers seeking a more challenging experience, the “Back Wall” of Molokini Crater offers a dramatic drop-off with depths exceeding 300 feet. This area is known for its strong currents and the presence of larger pelagic animals like sharks, manta rays, and even occasionally whales. Due to the depth and challenging conditions, diving the Back Wall requires advanced certification and experience. The dramatic depth and geology makes it one of the more challenging, but rewarding, dive sites in Hawaii.

The Northwestern Hawaiian Islands: A Hidden Archipelago

Extending far beyond the main Hawaiian Islands is a chain of smaller islands, atolls, and submerged reefs known as the Northwestern Hawaiian Islands (NWHI). This vast archipelago, now designated as the Papah&257;naumoku&257;kea Marine National Monument, is a largely pristine ecosystem that harbors a wealth of unique and endangered species. Many of the islands and atolls in the NWHI were formed by volcanic activity and have since been eroded and subsided, creating a complex mosaic of submerged reefs, lagoons, and shallow banks. Access to the NWHI is severely restricted to protect its fragile environment. However, scientists and researchers are actively studying the geological history and ecological significance of this remote archipelago. Papah&257;naumoku&257;kea is the largest protected conservation area in the United States, and one of the largest in the world, at over 583,00 square miles, which is larger and bigger than all the country’s national parks combined (Papah&257;naumoku&257;kea).

Observing Underwater Volcanic Activity Safely

While diving directly on or near active underwater volcanoes like L&333;&699;ihi is generally not possible for recreational divers, there are ways to experience and learn about these fascinating geological features safely. Look for documentaries and educational programs that feature underwater footage of volcanic activity. Some research institutions, such as HURL, occasionally offer public presentations or online resources that showcase their findings. Also, keep an eye out for museum exhibits that feature geological models and displays about Hawaii’s volcanic history. By staying informed and respecting the power of these natural forces, you can appreciate the beauty and wonder of underwater volcanoes without putting yourself at risk.

Responsible Diving and Snorkeling Practices

When exploring any marine environment, it’s crucial to practice responsible diving and snorkeling habits to minimize your impact on the ecosystem. Avoid touching or disturbing coral reefs or other marine organisms. Use reef-safe sunscreen to prevent damage to coral. Be mindful of your buoyancy and avoid stirring up sediment that can cloud the water and harm filter-feeding organisms. Respect all marine life and avoid feeding or harassing animals. By following these simple guidelines, you can help ensure that these underwater treasures remain healthy and vibrant for future generations.

FAQ Section

What is a seamount?

A seamount is an underwater mountain that rises from the seafloor but does not reach the surface. Many seamounts are extinct volcanoes. The Hawaiian-Emperor seamount chain is the largest example of this seamount formation.

Is it safe to swim near an active volcano?

Generally, no. Swimming or diving near active underwater volcanoes can be extremely dangerous due to the potential for eruptions, hydrothermal vents, and unstable geological formations. Scientists and researchers use specialized equipment and precautions when studying these environments.

Are there any laws protecting Hawaiian coral reefs?

Yes, there are several laws and regulations in place to protect Hawaiian coral reefs. These laws prohibit activities that damage or destroy coral reefs, such as anchoring on reefs, collecting coral, and using harmful sunscreen products. Always check the regulations for the specific area you are visiting.

What is the best time of year to dive in Hawaii?

Diving in Hawaii is generally good year-round, but the best conditions are typically found during the summer months (May to September) when the seas are calmer and the visibility is better. However, the winter months (November to March) can offer opportunities to see humpback whales, which migrate to Hawaii to breed.

Where can I learn more about Hawaiian volcanoes?

The Hawaii Volcanoes National Park on the Big Island is an excellent resource for learning about Hawaiian volcanoes. You can also visit the US Geological Survey’s Hawaiian Volcano Observatory website for up-to-date information and research about volcanic activity in Hawaii.

References

• Hawaii Undersea Research Laboratory, SOEST
• Hawaii Department of Land and Natural Resources
• Maui Guide
• Papah&257;naumoku&257;kea Marine National Monument
• Hawaii Volcanoes National Park
• US Geological Survey’s Hawaiian Volcano Observatory

Hawaii’s sunken volcanoes are a testament to the incredible power and dynamism of our planet, they continue to shape the islands we know and love. From the actively building L&333;&699;ihi Seamount to the vibrant reefs of Molokini, these underwater landscapes offer a unique glimpse into the geological history and ecological diversity of Hawaii. Even if you’re not an experienced diver, you can still appreciate these hidden gems by seeking out educational resources, supporting responsible tourism practices, and being mindful of the importance of preserving our marine environment. So, the next time you’re enjoying the beautiful beaches of Hawaii, remember that there’s an entire world of wonder waiting to be explored beneath the waves. Ready to plan your Hawaiian adventure? Start by researching local dive operators, booking a Molokini snorkeling tour, or exploring the Hawaii Volcanoes National Park to begin (or continue) your journey with these gems!