Telling time of day would be the first problem as it's always high noon. And star sightings might prove challenging, at least at optical frequencies.
(Am now thinking of an SF story set on the Sun in which navigation and timekeeping play critical roles....)
If the sun is always directly down from the surface, doesn't that make it solar midnight from anywhere on the surface?
(Focusing on the non-obvious problems might make for a more interesting and/or fantastical story.)
Teenage, mutant, ninja, or otherwise.
"Write a short (300--600 word) story about how human explorers on the Sun would address the challenges of navigation, orientation, and timekeeping (including the challenges of starfinding). Ignore obvious effects such as heat, gravity, and radiation."
Results are ... not excellent literature, but amusing all the same.