Manta ray snorkeling in Kona in May

Manta ray night snorkeling in Kona during May offers high manta activity, warm 77–79°F ocean temperatures, and calm sea conditions during Hawaii's spring shoulder season.

Manta ray night snorkeling in Kona during May offers high manta activity, warm 77–79°F ocean temperatures, and calm sea conditions during Hawaii's spring shoulder season. Excursions operate daily along the Kona coast as calm weather sets in for the warmer months.

May Conditions and Weather

May is considered a shoulder season sweet spot along the Kona coastline, combining favorable weather with smaller crowd sizes than the summer peak of July and August. Average air temperatures range from a low of 68°F to a high of 83°F, with dry weather and reliable calm evenings. Ocean water temperatures sit between 77°F and 79°F.

Sea conditions in May are among the calmest of the entire year for night snorkel trips. North swells are largely absent by May, while south swells remain small and long-period. Night snorkel tours run every night in May with rare weather cancellations. Humpback whales have generally left Hawaiian waters by May. New moon evenings during the month provide dark viewing contrast, which can enhance plankton concentration and manta activity.

Year-Round Seasonality in Kona

While May falls inside the optimal window from April through October, manta ray snorkeling in Kona is a year-round activity. Ocean water temperatures across Kona fluctuate between 75°F and 82°F depending on the season. Sighting success rates are among the highest in the world, commonly cited at 85–90% or higher.

Night snorkel tours are conducted from a lit platform floating at the surface and require no special certification. Standard tours typically offer around 60 minutes of total in-water time, with active swimming periods lasting between 20 and 45 minutes.

The Science of Kona Manta Encounters

Kona is home to resident reef mantas (Mobula alfredi), which reach adult wingspans of 8 to 16 feet. Unlike migratory species, these mantas stay in Kona year-round due to the island-mass effect. Steep underwater volcanic slopes push deep, nutrient-rich ocean currents upward to create a continuous, stationary plankton supply.

Rather than acting merely as cleaning stations where mantas get groomed, Kona's sites serve as active feeding stations. Submerged lights on float boards act as a dinner bell by gathering dense clouds of plankton. The resident mantas perform dynamic barrel rolls to filter feed just inches beneath floating snorkelers.

What to Expect and Bring

Tours last approximately 1.5 to 3 hours total, including a brief boat ride of 3 to 20 minutes (and as little as 3 to 5 minutes departing from Keauhou). Entry-level pricing starts at around $99+ per person.

Guests should wear a swimsuit under their clothes and bring a towel, warm dry layers for the boat ride back, reef-safe sunscreen, and motion-sickness medication. Operators provide masks, snorkels, lighted float boards, and wetsuits—a 3mm wetsuit is standard in May, though some participants prefer a shorty wetsuit. Personal cameras and GoPros are permitted, but flash lighting is prohibited because it disrupts the mantas. Snorkelers are frequently asked to forego fins to avoid accidentally kicking the animals.

FAQ

Are manta rays safe to snorkel with?

Manta rays are completely harmless and have no stinger or barb. While they often pass within inches of snorkelers while feeding, participants must remain flat on their float board and never touch the mantas.

What happens if no mantas appear on a May tour?

Most operators feature a Manta Guarantee. If no mantas are sighted during your tour, you can typically rebook or join another trip for free, though cash refunds are generally not offered. Exact terms vary by operator.

Do manta ray tours operate during the daytime?

Mantas are rarely seen during the daytime because they feed near lit boats at night. During daylight hours, mantas move into deeper water or visit cleaning stations.