Yes, several expeditions have successfully reached the bottom of the ocean. The most famous descent occurred in 1960 when Jacques Piccard and Don Walsh took the bathyscaphe Trieste to the Challenger Deep in the Mariana Trench, the deepest known point in the world's oceans, at about 36,000 feet (over 10,900 meters) deep.
Since then, there have been other explorations of the deep sea, including research missions using submersibles and remotely operated vehicles (ROVs). Notably, filmmaker James Cameron made a solo descent to the Challenger Deep in 2012 in the Deepsea Challenger submersible.
In addition to these historic explorations, there have been various scientific missions to explore different parts of the ocean, contributing to our understanding of deep-sea ecosystems and geology.