NERO DEEP

In 1875, onboard the HMS Challenger, the British oceanographic exploration expedition commanded by Captain George Strong Nares, recorded a depth of 26,850 feet near the southern end of the deep sea trench now known as the Marianas Trench. In 1899 the USS Nero recorded a depth of 31,693 feet southeast of Guam. This was the greatest depth recorded on earth at the time.  Since then, the deepest sounding for the Marianas Trench has been recorded at 35, 463 feet and remains the greatest depth on earth.