Tongan Volcano Adventure

A SetSailor recently sailed onto the scene of a volcanic eruption near Tonga, where he witnessed the birth of a new island. Fredrik Fransson of Maiken has sent us a gripping account with incredible photos of the experience.

sailing through pumice

We left Neiafu in the Vava’u group of islands in the northern part of Tonga on Friday the 11th of August, sailing towards Fiji. There was no wind, so we motored along towards an offshore island called Late Island. We had seen on the chart that Metis Shoal and Home Reef in the area were known for volcanic activity. Both are south of Late Island, so we thought it was best to pass it on the north side. Fairly soon we discovered brown grainy streaks in the water. It looked like heavy oil mixed with water. The surrounding water was strangely greenish, like a lagoon, not the deep bluish color that you normally see sailing offshore. The further southwest we got, the streaks turned into heavy bands of floating matter, until the whole horizon was a solid line to what looked like a desert.

sailing through volcanic rock

So far we didn’t have a problem, since it was such a thin layer on the surface which got pushed away by the bow wave – but when we entered the solid field, it started to pile up, and behaved like wet concrete. The sight was unbelievable; it looked like rolling sand dunes as far as the eye could see. Our speed went from 7 knots down to 1 as the pumice stones dragged along the waterline. I have always been very proud of my Awlgrip paintjob and the fresh bottom job, so my thoughts went immediately to what was happening with that. We turned around as quickly as we could and headed back the same way we came, towards clear water. As we hit clear water, we turned off the engine and cleaned the raw water strainer. The pumice stone floats, so some small pebbles had made it in to the strainer, but mostly they just clogged up the strainer on the outside of the hull. The worst place was the intake to the head, which was packed with the tiny pebbles.

pumice - effect on sailboats

We had no real idea what to do at that point, but we figured out what it must be and that it had to come from a volcanic eruption somewhere near. We joked around about the superstition of not sailing away on a Friday – you don’t get a stronger sign than that the ocean turned to stone! We were too far from land to contact anyone on the VHF radio, so our only options were either to sail south along the pumice rafts, or to head back to the islands. I wanted to make sure that everything was ok with the boat before heading off for a longer passage, so we decided to head back towards land and anchor for the night.

The next day we put out a call on the radio with a request for any information about the volcanic eruption, and got an answer that confirmed it, but did not know anything about its whereabouts. We knew that there were two places that have seen volcanic activity in the past, so we decided to sail south of both of them to avoid the pumice rafts that were drifting northwest. We motored out early that morning, heading SSW. We encountered the pumice rafts and sailed along them, until they were so broken up that we could safely drive through them.

photos of pumice

We collected a few stones, some a big as a soccer ball – but the bigger they were the more brittle they were, and with the motion of a sailboat they eventually broke into pieces. I am not a scientist, but someone told us that pumice is actually a kind of glass, and when you looked at the bigger pieces, you could really see that structure. Soon we could make out that one of the clouds on the horizon weren’t clouds at all, but actually a smoke stack from the active volcano. The smoke seemed to come from the Home Reef volcanic area. We had been planning to sail south of both these areas, but curiosity overcame us, so we headed toward the southern part of Home Reef.

photo of birth of volanic island

The closer we came to the island, the clearer the smoke stood out from the surrounding clouds, and every so often a massive black pillar shot upwards toward the sky. You could see particles raining down. Since the wind was pushing the smoke to the northwest, we decided to go in a bit closer. While the sun was going down, we motored up to within 1.5 nautical miles of the island. Later I put the coordinates to be 18deg.59.5S and 174deg.46.3W. It was smoldering with steam, but it was possible to get a good picture of it. You could clearly see the three mounds creating a crater, with one side breaking off, opening up towards the sea. It looked like a big island made of black coal. We reached down and felt the water, and it was warmer, although we didn’t actually measure the temperature difference.

Our concern at the time was to sail away from the island before it got too dark, as we didn’t know if we would encounter more pumice rafts. The pumice rafts do not show up on the radar, and since we didn’t know if this was the end of it, we headed SSW toward the southern part of the Lau group in Fiji.

It was an amazing experience to witness, although the waterline of Maiken was scratched a bit from all the pumice; I guess that is the price you pay. Since then we have heard of several sailors running into the pumice rafts, some even during the night, which must have been a frightening experience. I think with time the pumice rafts get a bit thinner and easier to penetrate, as we heard of vessels sailing through them, only losing some of their speed. When we were leaving Fiji in the middle of September, we still heard on the radio an account of the pumice drifting up on beaches in Fiji.

I got a bit surprised when much later a scientist with the Smithsonian Institute asked for details and photos, and somehow later it ended up with the Associated Press, which led to lots of media coverage. I have been told by another scientist at NASA that sometimes these islands do “disappear” with time, broken down by wind and wave action – but our island still shows up clearly on a satellite photo taken in the middle of October, so who knows.

photo of birth of volcanic island

Posted by Sarah.Dashew  (December 20, 2006)

One Response to “Tongan Volcano Adventure”

  1. Bill Dowd Says:

    I live on Bribie Island, about an hour north of Brisbane, Queensland, Australia. Recently a lot of pumice has been washing up on the eastern beach. A Queensland Uni of Technology vulcanologist stated in our local paper that this pumice probably came from an undersea volcano in the Tonga-Kermadec arc of volcanoes. 700 metres below the surface. I was very interested to read your account of your encounter with the pumice. Maybe that’s where this lot came from? Dozens of dead Sooty Shearwaters also washed up on the beach last October. These probably died of exhaustion during their migration the the islands further north. But apparently some of the birds had pumice in their gut. Interesting! Cheers Bill