It was suspected that hydrothermal activity did occur in subtidal areas in Eyjafjörður. The nature and exact location of these areas was however unclear and it proved difficult to prove these rumours. The location of chimneys was first confirmed by depth sounders on the research vessel Bjarni Sæmundsson in 1990. The first time large hydrothermal chimneys were found in such shallow waters.

The Ystuvíkurstrýtur chimneys are in fact three, located close to the middle of the inner part of Eyjafjörður fjord. The bottom depth around the chimneys is about 65 m and the highest of the chimneys reached about 45 m from the bottom. This is also the only chimney that is still hydrothermally active.

These submarine hydrothermal chimneys later became known as Ystuvíkurstrýtur (Ystuvíkur bay chimneys), named after a small bay close by. These chimneys are now protected as natural monuments, the first such marine area in Icelandic waters. This means that all use of fishing gear or anchor around them is prohibited. Special licence is required to collect scientific samples around them. However diving around them is allowed as long as they are not harmed.

The geology and microbiology of the chimneys was studied in 1997 and 1998, this was also the first time they were seen with bare eyes, both from a small submersible and by divers. Although these chimneys look in many ways like chimneys in deep sea vents, they are made of magnesium cilicate clay while deep sea chimneys are made of anhydrite. The water from the chimneys is fresh and has been measured at about 72°C.

HV

Kafarar við topp stærstu ystuvíkurstrýtunnar (mynd Erlendur Bogason) Kafarar við topp stærstu ystuvíkurstrýtunnar (mynd Erlendur Bogason)