Needed to get over to the mainland to get some stuff done. After past couple days of not flying there was a lot of pent up demand, and early flights were full. Had a seat on the noon plane (Piper 26 - 28), with 2 other passengers. The pilot said we should wear our seatbelts, which I always do. Wish he'd said it was going to be especially bumpy, and the belts should be tight. As soon as we lifted off it was the roughest ride I've ever been on. Plane dropped out from under me (I was lifted entirely off the seat), slammed against the door next to me then tossed the other way across the seat (luckily there was nobody there). Couldn't get my hand down to tighten the belt. Never been airsick, but came close. Once landed I got some gingerale and crackers to settle my stomach. But there was finally mail. Have a package at the post office I'll get tomorrow.