8.850 kilometers is about four-fifths as deep as The Challenger Deep (Marianas Trench)
In other words, it's 0.811780 times the depth of The Challenger Deep (Marianas Trench), and the depth of The Challenger Deep (Marianas Trench) is 1.23190 times that amount.
(near Marianas Islands, a.k.a. Ladrones Islands, northwestern Pacific Ocean) (depth below sea level) The Challenger Deep, at the southern end of the Marianas Trench, reaches a depth of 10.902 km below sea level. The first manned expedition to the bottom of Challenger Deep took 4 hours and 48 minutes in 1960. This was the only manned descent to the floor of the Trench until 2012, when director James Cameron made the trip; several other descents have been made since then.