Can a compass work underground ?

Would a traditional compass work beneath the surface? The compass app on your phone probably won’t work because it relies on radio signals that are easily blocked by rock or water, but for a compass with a wobbly needle, it just depends on how far underground. A compass works because its magnetized needle lines up with the magnetic field that runs between Earth’s north and south poles, and that field is just as powerful if you go down a mine shaft or into the depths of the ocean. But the field is created by swirling molten iron in Earth’s core, and if you could drill that far down, you’d find your magnetic needle going haywire.