Challenger Deep

On 23 January 1960, the Swiss-designed Trieste, originally built in Italy and acquired by the U.S. Navy, descended to the ocean floor in the trench manned by Jacques Piccard (who co-designed the submersible along with his father, Auguste Piccard) and USN Lieutenant Don Walsh. Their crew compartment was inside a spherical pressure vessel, which was a heavy-duty replacement (of the Italian original) built by Krupp Steel Works of Essen, Germany. Their descent took almost five hours and the two men spent barely twenty minutes on the ocean floor before undertaking the three-hour-and-fifteen-minute ascent. Their early departure from the ocean floor was due to their concern over a crack in the outer window caused by the temperature differences during their descent. The measured depth at the bottom was measured with a manometer at 10,916 m (35,814 ft) ±5 m (16 ft).

Question: has anything been to the bottom of the ocean
Answer: yes