There were plenty of gasps and "wow"s ringing out from the Bridge Club rooms as people enjoyed a guest speaker's talk about submarine drilling at Brothers volcano.
The guest speaker at Rotorua U3A's forum on Wednesday was Dr Cornel de Ronde, a New Zealand expert on undersea volcanic activity and mineral deposition.
He is currently a principal scientist and research geologist with GNS Science.
At the forum he talked about his recent exploration of the Brothers volcano in the Kermadec volcanic ridge.
About three times the size of White Island, the Brothers volcano is located some 400km north-east of White Island and more than 1km below the surface, where it is spewing large amounts of volcanic gases and superheated seawater into the ocean.
This process has formed hundreds of spectacular black smoker chimneys rich in gold, copper and zinc, and creating extreme environments where unusual life forms thrive.
Cornel was co-chief scientist on US deep-sea drilling research ship the JOIDES Resolution which in May/June last year drilled a series of holes into the volcano to discover, among other things, how mineral deposits such as copper and gold are formed on the seafloor.
Cornel says scientists have been exploring Brothers volcano since 1999.
He says it is important to share these experiences and this information because it is all about understanding our natural world - including how volcanoes form offshore and how important are their associated hydrothermal systems.
Cornel says New Zealand is host to a lot of volcanic activity - yet many people do not realise New Zealand has a very large marine estate compared with its land size where there are many submarine volcanoes.
He says some submarine volcanoes form spectacular mineral deposits, including zinc, copper and gold, and that they make for a fantastic potential resource for New Zealand.
"Another thing they do is host an incredible diversity of life ... and we even find new species every time we go."
Cornel says when doing these types of talks he enjoys hearing the gasps of people's surprise and amazement from seeing some of his underwater videos.
"Much of what we do is about education, but it's about discovery and adventure. These volcanoes and hydrothermal systems are all in our backyard and there's still so much to explore."
He says these types of expeditions and research he and his colleagues do are difficult and expensive to do.
"We are very lucky in New Zealand because we have this wonderful natural research 'sandpit', so people overseas bring their sophisticated 'toys' and together we work towards a common goal of understanding these systems.
"New Zealand as a nation has, for many decades, looked inwards at the land. Maybe it's about time we turned our attention to the oceans surrounding us for our food, energy and mineral resources."