Keep in mind that I was not a part of the crew.

We had a PAX on the EMB that was flying from West Yellowstone to SLC. He started to freak out saying that the aircraft was flying at 4K which was way too low and well below the mountains in that area. The FA called the CA and made him aware of the developing problem. The CA told the FA that they were safely at FL220 and well above the terrain. The passenger didn’t believe the FA and continued to cause problems. Once on the ground the CA had the GSC and security meet the aircraft. Come to find out he had a pressure sensing dive watch that was telling him the aircrafts cabin altitude.

HAHAHAHAHAAAAAA! Ignorance is bliss.