"Human walk" here means movement primarily powered by the reaction forces of physical contact between a solid surface and multiple separate alternating appendages that are controlled by and contain legs that are part of a living and conscious biological human. Therefore, in addition to counting common sense stuff like people wearing standard diving gear and space suits, this also counts edge case existing stuff like atmospheric diving suits or hypothetical things resembling sci-fi power armours, even if the limb movement is primarily driven by motors, as long as this movement is ultimately directed by the movement of the human's legs inside.
"Conscious" above means being able to perceive and remember sensory input, so for example if someone is completely knocked out by nitrogen narcosis or their experience is completely taken over by hydrogen narcosis hallucinations then that wouldn't count.
"On Challenger Deep' here counts the seabed anywhere below 10,900m depth in either of the western, central, or eastern pools.
Some relevant info for context:
At Challenger Deep, the temperature is ~2.6 °C (~37 °F) and the pressure is ~1,100 atm
The atmosphere of Venus is mostly carbon dioxide, with a thick cloud layer of sulfuric acid. At the mean surface level, the temperature is ~460 °C (~870 °F) and the pressure is ~92 atm, turning the lower atmosphere into a supercritical fluid
However, at the top of the Maxwell Montes on the Ishtar Terra continental highland, ~11 km above the mean surface level, the temperature is only ~380 °C (~720 °F) and the pressure is only ~44 atm
https://en.wikipedia.org/wiki/Maxwell_Montes
In ambient pressure diving, various illnesses are caused by breathing gases at high pressures, requiring specialist breathing gas mixtures to avoid:
Nitrogen narcosis becomes significant below 30m (~4 atm)
Oxygen toxicity becomes significant below 60m (~7 atm)
High pressure nervous syndrome / helium tremors become significant below 150m (~16 atm)
Hydrogen narcosis becomes significant below 300m (~31 atm)
Remarkably, the record ambient pressure dive in the ocean is ~530m, and the highest pressure simulated dive in a hyperbaric chamber is ~700m
For atmospheric diving suits, the record dive in the ocean is ~610m
https://en.wikipedia.org/wiki/Atmospheric_diving_suit
and the highest pressure simulated dive in a hyperbaric chamber (that I could find) is ~900m
https://en.wikipedia.org/wiki/Newtsuit
The Apollo space suits are capable of protecting from temperatures ranging from −156 °C (−249 °F) to 121 °C (250 °F)
https://en.wikipedia.org/wiki/Space_suit
The longest surviving probe on the surface of Venus so far is the Venera 13 lander in 1982 at 127 minutes
https://en.wikipedia.org/wiki/List_of_landings_on_extraterrestrial_bodies
So essentially this comes down to whether we'll be able to reach a far away place within record pressure but way above record temperature, or a near place within normal temperature but way above record pressure.
1,000