Hawaii island tour boat companies are being cautioned to operate with greater safety in mind when running tours to view the spectacle of hot lava spilling into the ocean.

In a letter sent to operators, Hawai‘i Volcanoes National Park Superintendent Cindy Orlando noted that her staff has documented unsafe activities in the ocean near the Kamokuna lava entry.

“Boats have been observed going into and through the plume generated by the ocean entry,” Orlando wrote in the letter. “This is a serious safety hazard due to fine volcanic particles and hazardous gases.”

Danielle Foster, National Park Service environmental protection specialist, said Friday that park officials have already discussed concerns about the safety issues with other government agencies.

Even park visitors have complained to rangers and questioned how close the boats are getting, she said.

“I wouldn’t go on one of those boats because I feel they get too close. I’m not willing to take the risk,” Foster said.

Several operators could not be reached for comment Friday, but their websites tout the safety of their tours, and several social media posts mention it as well, including this one on Facebook in September by Linda Rhodes of Durham, N.H.:

“We were able to see the lava, and I was blown away by how close we got to it — the captain was careful about safety, yet skilled enough to get the boat very close — I could feel the heat coming off the lava, and the water was boiling under the boat. A really transformative experience and worth every penny.”

Orlando’s letter also warns of safety risks with operating near the lava flow due to potential bench collapses and molten material being ejected from the explosive reaction with the sea.

On New Year’s Eve, a 26-acre lava delta collapsed into the ocean, including a section of more established coastal cliff area.

The collapse started in the afternoon and lasted several hours, creating blasts of volcanic rock and a series of damaging waves, in addition to a thick, dark plume of debris and gas, officials reported at the time.

Foster said it was fortunate no tour boats were in the vicinity of the collapse.

And while the current lava flow is pouring directly into the ocean, she said, it won’t take long for a new unstable bench to develop, creating another hazard.

Following the collapse, park rangers set up a new lava viewing area about 900 feet east of the cascading lava and about 60 feet inland of the coastal cliffs.

The National Park Service previously worked with the Federal Aviation Administration to issue a temporary flight restriction extending to 1,000 feet above ground.

According to the U.S. Geological Survey’s Hawaiian Volcano Observatory, venturing too close to the ocean entry exposes one to flying debris created by the explosive interaction between lava and water.

What’s more, the interaction of lava and ocean water generates a corrosive seawater plume laden with hydrochloric acid and fine volcanic particles that can irritate the skin, eyes and lungs.

In other developments, park officials said they are analyzing the use of drones to determine potential impacts on “park resources, visitors and values.” So far, no requests to fly unmanned aircraft have been approved to view the lava, according to Orlando.