safe and sound (thinking about tent 2)

googling for the origins of safe and sound I found these quotes:

"As a nautical expression, I believe that it was originally: safe IN sound, as a sound is an inland body of water coming off of an ocean. So if a boat got driven in by a storm, that is where it would find refuge.

Sound is also used as a nautical term as a verb: meaning to measure or probe the depths or to dive quickly

Safe and sound... to be sound means: in good condition, free from defect or damage, secured, having a firm foundation.

Safe means to be out of harm's way. So "safe and sound" would mean that a person is no longer in harm's way and they are in good condition/undamaged."