We really need to create some submersible vehicle that can withstand the pressure of the deep ocean, I just know there's some creatures that we know of and some creatures that we don't.
Look at this mess
Giant Squid
Frilled shark, termed a living fossil
Vampire squid
Chimaera aka ghost shark
Grenadier
Fangtooth
Giant tube worms, these dwell in total darkness
So if these creatures dwell several hundred feet (aka several meters) under water, with little light and extreme temperatures, just imagine what's even further down in the oceans.
Look at this mess


Frilled shark, termed a living fossil

Vampire squid

Chimaera aka ghost shark

Grenadier

Fangtooth

Giant tube worms, these dwell in total darkness
So if these creatures dwell several hundred feet (aka several meters) under water, with little light and extreme temperatures, just imagine what's even further down in the oceans.