The bottom of the oceans are great unexplored areas on our planet. The extreme high pressures and great depths that need to be descended to makes one of the hardest places on the planet to discover and there are many potential discoveries and advances in science that could be made by studying them in more detail.
In particular the potential for microbiotic life around thermal vents (ie mini underwater volcanoes) is one topic that interests me.
Lots of microbes and weird new fish or crustaceans that we know nothing about is my guess! We have probably explored the ocean the least of everything- we spend so much time looking out into space, but not very much researching the vast expanse of water on the planet. It’s difficult to find out the answer to your question because of the high pressures in the ocean depths- we need to create new technologies that are able to withstand a lot. There are so many discoveries to make in the ocean, maybe one day you could be the person that invents the robot that shows us the ocean floor?