On 25 April, the boundary was extended to a depth of 18 miles.

Its pride was Alvin, which could carry three people to a depth of 2.5 miles.

Russian scientists reported at Utrecht that over 20 years they had reached depths of more than two miles.

That would cover the United States to depth of about 4 miles.

Taken together, the team says, the evidence suggests that the Swiss rocks came from a depth of 250 miles to 415 miles.

Scientists have tracked these whales to depths of 1.2 miles, and assume they might go deeper.

It was now but 140 degrees, although we had penetrated to a depth of nearly four miles.

At a depth of nearly ten miles I stopped and looked at the Professor.

The boundary between the mantle's upper and lower layers is at a depth of 400 miles.

At a depth of two miles, Tom switched on the directional jets.