Diving with Manta Rays: A Guide to Encountering These Majestic Giants

By Sorrasek Phiboonthammasak Date 25 Apr 2025

Manta rays, the largest ray species on Earth, are a bucket-list sighting for scuba divers worldwide. Picture this: while scuba diving, a massive, dark, diamond-shaped shadow glides gracefully into view, moving with serene elegance. The initial shock quickly transforms into awe as you become captivated by their fluid movements and sheer size. In this article, we’ll dive into what manta rays are, the differences between oceanic and reef manta rays, where and when to scuba dive with them—especially in Thailand—and how to behave around them for the best experience.

What is a Manta Ray?

Manta rays are large, cartilaginous fish belonging to the family Mobulidae, closely related to sharks and other rays. Known for their impressive size, they can grow up to 23 feet (7 meters) in wingspan and weigh as much as 3,000 pounds (1,350 kg). Unlike stingrays, manta rays lack a venomous tail spine and are harmless to humans, feeding primarily on plankton and small fish through filter-feeding. Their distinctive cephalic fins, which resemble horns, guide food into their wide mouths as they swim. Manta rays are highly intelligent, with one of the largest brain-to-body ratios among fish, and exhibit curious and gentle behavior around divers.

These majestic creatures inhabit tropical and subtropical waters, often near coral reefs or rocky outcrops where food is abundant. They are known for their acrobatic barrel rolls while feeding and their visits to cleaning stations where small fish remove parasites from their skin. Unfortunately, manta rays face threats from overfishing, bycatch, and habitat degradation, leading to their classification as vulnerable by the International Union for Conservation of Nature (IUCN).

Source: IUCN Red List of Threatened Species, Mobula birostris and Mobula alfredi, available at https://www.iucnredlist.org.

What is the Difference Between Oceanic and Reef Manta Rays?

There are two primary species of manta rays: the oceanic manta ray (Mobula birostris) and the reef manta ray (Mobula alfredi). While they share many similarities, they differ in size, habitat, and behavior:

Size: Oceanic manta rays are larger, reaching wingspans of up to 23 feet (7 meters), while reef manta rays are smaller, typically growing to about 18 feet (5.5 meters).
Habitat: Oceanic manta rays are pelagic, roaming open ocean waters and occasionally visiting coastal areas. Reef manta rays prefer coastal environments, often residing near coral reefs and rocky outcrops.
Behavior: Oceanic manta rays undertake longer migrations across vast ocean expanses, while reef manta rays are more residential, staying closer to specific reefs or cleaning stations. Reef mantas are also more likely to form aggregations in areas with abundant food or cleaning opportunities.
Coloration and Markings: Both species have unique ventral spot patterns used for identification, but oceanic mantas often have darker dorsal surfaces, while reef mantas may display lighter or more varied coloration.
Reproduction: Both species are ovoviviparous, giving birth to live pups, but reef mantas tend to have smaller litters and more frequent interactions with divers due to their coastal habits.

Understanding these differences helps divers identify which species they’re encountering and appreciate their unique behaviors.

Where to Scuba Dive with Manta Rays Around the World

Manta rays inhabit tropical waters, making them accessible to scuba divers in various global hotspots. However, their slow reproduction rates and past overfishing have reduced their populations, meaning sightings are most reliable in protected marine areas. Here are some top destinations:

Thailand: Dive sites like Similan Islands and Richelieu Rock in the Andaman Sea are renowned for manta ray encounters.
Indonesia: Raja Ampat and Komodo National Park offer frequent sightings, with nutrient-rich waters attracting mantas.
Philippines: Tubbataha Reefs Natural Park is a prime location for spotting mantas.
Maldives: Hanifaru Bay is famous for “manta trains,” where dozens of mantas feed in plankton-rich waters.
Hawaii, USA: Night dives off Kona provide opportunities to see mantas attracted to plankton by dive lights.
Mexico: Socorro Island in the Revillagigedo Archipelago is known for close encounters with mantas.
Ecuador: The Galapagos Islands offer dives with both oceanic and reef mantas in nutrient-rich waters.

These protected areas ensure manta rays continue to thrive, offering divers a chance to witness their grace.

Where to Meet Manta Rays in Thailand

Thailand is a top destination for divers seeking manta rays, particularly in the Andaman Sea. Liveaboard trips to destinations like Similan, Khao Lak, Phuket, Krabi, or Koh Lipe provide the best opportunities. Note that manta ray sightings are rare in the Gulf of Thailand. Below are the top dive sites in the Andaman Sea where conditions favor manta ray encounters. Keep in mind that manta rays are wild animals, so sightings are not guaranteed, but these locations offer the highest probability:

Koh Tachai: This complex rock structure with strong currents attracts plankton, making it a feeding ground for mantas. Visibility can be low due to plankton blooms and currents.
Koh Bon: A giant rock serves as a cleaning station where cleaner wrasse tend to mantas, making it a hotspot for sightings.
Richelieu Rock: This horseshoe-shaped pinnacle teems with plankton and marine life, drawing mantas to feed. Divers should scan the blue for approaching shadows.
Similan Islands: A protected national park with excellent visibility and abundant nutrients, ideal for spotting mantas in their full glory.
Hin Muang and Hin Daeng: These twin rock pinnacles in South Andaman are covered in soft corals that trap plankton, attracting mantas to feed.
Racha Islands: A short 1.5-hour boat ride from Phuket, Racha offers stunning visibility but lower manta sighting chances due to boat traffic.
8 Mile Rock: Near Koh Lipe, this submerged pinnacle is a navigational waypoint for mantas, who visit to feed, clean, or pass through.

When is the Best Time to Spot Manta Rays in Thailand?

The best time to dive with manta rays in Thailand aligns with the Andaman Sea’s dry season, from October to May. During this period, sunny weather, calm seas, and cool breezes create ideal diving conditions, and national parks like Similan, Koh Surin, Koh Bon, Koh Tachai, and Richelieu Rock are open. For 8 Mile Rock near Koh Lipe, the diving season extends from October to July, though May to July may bring rain.

For optimal conditions and the highest chance of manta ray sightings, plan your trip between December and February, when visibility and weather are at their peak.

Manta Ray Behavior and Encounters

Understanding manta ray behavior enhances your diving experience and ensures respectful interactions. Manta rays exhibit three primary behaviors underwater: feeding, cleaning, and navigating.

Feeding: As filter feeders, manta rays consume zooplankton by swimming with their mouths open, often against currents to funnel water through their gills. They may perform barrel rolls or somersaults near the surface to trap plankton, especially when food is concentrated.
Cleaning: Manta rays visit cleaning stations, typically rock pinnacles or reefs, where cleaner fish like wrasse, butterflyfish, or angelfish remove parasites from their skin. Mantas hover calmly, sometimes queuing with other rays or sharks, resembling a marine “car wash.”
Navigating: Mantas often glide through reefs while migrating, heading to feeding grounds, or approaching cleaning stations. They may appear from open water, so divers should stay alert.

By recognizing these behaviors, divers can anticipate manta movements and interact responsibly.

How to Scuba Dive with Manta Rays

To ensure a safe and enjoyable experience for both divers and manta rays, follow these guidelines:

Don’t Chase: Resist the urge to pursue mantas, as this can scare them away and disrupt their behavior. Chasing also risks disorienting divers in strong currents.
Don’t Touch: Touching mantas can damage their protective skin coating, making them susceptible to infections. It’s also unsafe, as their size and movements can unintentionally harm divers.
No Flash Photography: Avoid using camera flashes, which can startle mantas and alter their behavior, especially near their sensitive eyes.
Stay Still and Calm: Remain stationary and relaxed, whether mantas approach you or linger at a cleaning station. If they feel unthreatened, they’re more likely to stay, offering extended viewing opportunities.

These practices preserve the natural behavior of manta rays and enhance your dive.

My Personal Experience with Manta Rays

I’ve been fortunate to encounter manta rays twice in Thailand: once at Hin Muang and Hin Daeng, and once at Koh Tachai. Each sighting felt like a privilege. At Hin Muang and Hin Daeng, the first dive of the day was magical—perfect visibility, vibrant soft corals, and clear light. As I marveled at the reef, a whale shark appeared, followed moments later by a manta ray gliding from the other side of the pinnacle. The sheer size and serene grace of these creatures left me in awe, their slow, steady movements creating a sense of calm. It’s moments like these that remind divers why we explore the underwater world.

Ready to Meet Manta Rays?

Now that you’re excited to dive with manta rays, it’s time to plan your adventure! I’m Benz, owner of Giant Stride, with over seven years of diving experience in Thailand. If you’re considering a scuba trip, contact me to plan your itinerary at no extra cost, or explore our liveaboard options for North or South Andaman trips, both offering excellent chances to see manta rays. Visit our website for the best price guarantee on Thailand dive trips. Have questions about manta rays or diving in Thailand? Let us help you make your dream a reality!

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