The people who first visited the depths of the Mariana Trench were oceanographers Don Walsh and Jacques Piccard who visited Challenger Deep together aboard the Bathyscaphe Triest in the year 1960.
Then the third person who visited the Mariana Trench in 2012 was James Cameron who reached the depths of the Mariana Trench on March 26th 2012.
No one else has yet to reach the depths of the Mariana Trench other than those 3 people.