SPG (Submersible Pressure Gauge) — What It Is and Why It Matters

An SPG (submersible pressure gauge) is a mechanical gauge connected to a high-pressure port on the regulator's first stage that displays your remaining tank pressure in real time. It is the analog alternative to air integration — simple, reliable, and battery-free. SPGs use a Bourdon tube mechanism that has been proven over decades of diving.

SPGs are often mounted in a console alongside a depth gauge and compass, though minimalist configurations clip the SPG as a standalone instrument on a short hose. Many divers carry an SPG as a backup even when using air-integrated dive computers, as a mechanical gauge never loses wireless signal or runs out of battery.