Visitor charged after stabbing snorkel boat captain off Kona coast

Passengers aboard a Kona snorkel trip helped stop a violent attack at sea, restraining a 21-year-old visitor after he allegedly stabbed the captain with a fillet knife during a three-hour tour off the Kona coast.

Hawaiʻi Island police said the assault happened Thursday, April 16, 2026, at about 3:21 p.m. off the Kona coast. Officers responded to Honokōhau Harbor after a fishing vessel returned from sea with both the victim and suspect still onboard. The suspect was identified as Avery Nissen, 21, of Overland Park, Kansas.

Police said the captain was 62 years old. During the tour, other passengers intervened and held Nissen down until authorities arrived. The captain suffered a stab wound to the lower abdomen, along with knife cuts to his head and hands, and was taken to Kona Community Hospital. He remained in stable condition.

The motive for the attack remains unknown. After consulting with the Office of the Prosecuting Attorney, police charged Nissen on Friday, April 17, 2026, with second-degree attempted murder, first-degree assault and second-degree assault. His bail was set at $1,570,000, and his initial court appearance is scheduled for Monday, April 20, 2026, in Kona District Court.

The case carries immediate consequences for Kona’s visitor industry, where snorkel charters and ocean excursions are a routine part of the local economy. A single onboard assault can force operators to revisit how crews screen passengers, secure sharp tools, and train for emergency restraint before a disturbance turns into a medical crisis. In West Hawaiʻi, where tour boats, fishing vessels and dive charters move daily through the same waters, safety procedures are part of the product as much as the scenery.

The attack also comes amid other recent Big Island water-related investigations, including separate April cases involving possible drownings in Kailua-Kona and Keauhou. Together, the incidents have placed renewed attention on how quickly routine maritime outings can turn into urgent rescue scenes.

Police asked anyone with information to contact Detective Bradley Llanes at the Hawaiʻi Police Department.