Fred . . .
You have the right idea, you can get out of the bunker and the penalty is one stroke, but the Rule is specific. Under Rule 25-1b (ii) (b) on page 75, the player is directed to keep the point where the ball lay in the bunker between the hole and where the ball is dropped with no limit as to how far one can go back to drop a ball. It doesn’t have to be the ball, in case it’s hard to retrieve, it’s a ball.
The other day, after heavy rain the night before, I played a course and on the 3rd hole I hit my drive into the near (towards the tee end and away from the green end) of a bunker. That end of the bunker was completely full of (casual?) water, right up to the grass edges, no sand (muck!) available to drop within the bunker, my ball lay in the casual water near the tee end of the bunker. I took relief no nearer the hole but outside the bunker, taking a penalty stroke, and played on. Did I handle this situation correctly? Thanks.