The scientists said they were delighted to witness the eruption of Australia's second-tallest mountain on Heard Island, 4,100km south-west of Perth.
Big Ben is known to have erupted at least three times since 2000, but such eruptions are rarely witnessed.
Heard island is dominated by the Big Ben massif and its summit, Mawson Peak.
The scientists on board the research vessel Investigator, who are researching whether active undersea volcanoes support life in the Southern Ocean, said they were thrilled to witness the eruption.
Lava flows beneath ice
Professor Mike Coffin, a geophysicist from the University of Tasmania's Institute for Marine and Antarctic Studies (IMAS), called the experience "an amazing coda to this week's submarine research".
"We saw vapour being emitted from the top of the volcano and we saw lava flows coming down the flank of Big Ben," Prof Coffin, the voyage's chief scientist, said. Read more on bbc.