[ErnstStavroBlofeld]

Maybe a new Project Mohole. If anyone knows what that project was it was an attempt to drill through the Earth's crust to the boundary between the crust and the mantle. The drilling was to begin at the ocean bottom because this is where the crust is at its thinnest.They never completed it because it ran into cost over runs. The deepest they got was something around 600 feet below the ocean's floor in 11,000 feet of water.

[ApplegateRanch]

Successor program:

Scientists Aboard Drilling Vessel Recover Rocks from Earth’s Crust Far Below Seafloor

April 5, 2005

Scientists affiliated with the Integrated Ocean Drilling Program (IODP) and seeking the elusive “Moho”—the boundary, which geologists refer to as the Mohorovicic discontinuity, between Earth's brittle outer crust and its hotter, softer mantle—have created the third deepest hole ever drilled into the ocean bottom’s crust.

[snip]

From the ocean drilling vessel, JOIDES Resolution, the researchers recovered rocks from more than 4,644 feet (1416 meters) below the sea floor that will provide valuable information about the composition of the Earth. And despite coming up short, “This is one of the best efforts to date,” said Rodey Batiza, NSF program director for ocean drilling, “to drill into ocean crust and find mantle. It will provide important clues on how ocean crust forms.”
[end excerpt]

Earth's elusive mantle is a near miss They may be using the wrong approach...there are better ways: