Flying from Guam (GUM) to Hawaii (HNL) typically takes around 7 hours. Due to the significant time zone difference between Guam and Hawaii, the local time upon arrival in Hawaii will indeed be much earlier than the departure time in Guam. Guam is in the Chamorro Standard Time (ChST) zone, which is UTC+10, while Hawaii is in the Hawaii-Aleutian Standard Time (HST) zone, which is UTC-10. This means there is a 20-hour time difference between Guam and Hawaii. For example, if you depart from Guam at 8:00 AM ChST, after a 7-hour flight, you would arrive in Hawaii at around 3:00 PM HST on the previous day. This results in “going back” 13 hours on the clock, despite the 7-hour travel time. This substantial time difference can be quite disorienting but is a common experience when traveling across the International Date Line and between drastically different time zones.