Could drilling into the mantle cause a quake like the one on Boxing Day 2004?
Scientists from Cardiff University are behind the mission, which hopes to bring the first ever samples of mantle - the rocky substance that makes up most of our planet between the crust and core - back to the surface to be studied.
But the team also wants to investigate an area at the very heart of the seismic activity which triggers earthquakes and volcanoes.
Professor Chris MacLeod, project co-leader, wants to investigate an area at the edge of the crust and mantle called the Moho boundary.
It is a place where the seismic waves of earthquakes suddenly change speed.
This is because they go from the crust is made up of hard igneous rocks like granites and basalts, into the softer mantle.
The area in question is called Atlantis Bank on the South West Indian Ridge of the Indian Ocean.
It was chosen because faults and erosion have already thinned the crust there.
The International Ocean Discovery Program (IODP) project could allow scientists to examine for the first time untouched peridotite from the mantle a rock, rich in olivine minerals makes up the bulk of our world inside.
However, drilling into such a seismically significant area has prompted fears the project could be a disaster and trigger a huge earthquake or volcano.
Many scientists and campaigners now believe there is a direct link between deep drilling and man-made earthquakes.
The arrow shows the location in the Indian Ocean of the planned drilling
Scientists say that massive earthquakes would only happen in shallower water because of the pressure on top of them at deeper levels.
However, geologists were left perplexed by a magnitude-8.3 earthquake that suddenly happened on May 24, 2013, in the Sea of Okhotsk, deep within the Earth's mantle.
Thorne Lay, a seismologist at the University of California, Santa Cruz and co-author of a study into it, said: "It's the biggest event we've ever seen.
"It looks so similar to shallow events, even though it's got 600 kilometres of rock on top of it.
"It's hard to understand how such an earthquake occurs at all under such huge pressure."
It happened at a crack where the Pacific Plate was pressing into the mantle, and was felt in Russia, but fortunately no one was hurt.
If an under-sea quake was big enough it could trigger huge tsunamis like those of Boxing Day 2004 which hit south-east Asia after an earthquake in the Indian Ocean.