Here's a vintage 1970s Nicolet diver with the rare depth gauge tube around the edge of the dial. The water enters at a tiny opening at the 3...and the rest is for divers!
Check out the stone-brown dial with orange seconds hand and that amazing golden bezel.
This solid stainless steel behemoth is 42mm wide, excluding the unsigned screw-down crown, by 48mm from lug to lug.
Under the hood is a manual winding Valjoux 7733, keeping excellent time.
Massive. Cool. What else could you want?
For those who seek a fuller explanation of the tube, here's what the previous owner wrote:
When the watch is submerged, the opening of at the 3 is blocked by water. The air inside the tube is trapped. The deeper a diver goes, the more air in the tube gets compressed as water moves further into the tube. The tube is normally opaque in the air. But as the water moves around, the tube becomes transparent because there is a metal ring under the crystal that reflects against the water.
Now you know.