What to Put in a Dive Logbook, Beyond Depth and Time

A dive center checking your logbook is usually looking for three things: a recent date, a depth that matches what you’re asking to do, and a certification card that backs it up. Everything else in a logbook is there for you, not for anyone checking it — but it’s the part that makes the log worth keeping past the first stamp.

The minimum that gets checked

Before certain dives — deep, wreck, night, or anything past what your base certification covers — a dive center typically wants to see: your certification level and card, a rough dive count, and how recently you’ve been in the water. “Rough” is doing a lot of work in that sentence. Nobody counts your dives for you; they trust the number in your book, which only works if you’ve actually been logging.

The part that makes a logbook useful to you, later

Past that minimum, the entries that make a logbook worth having are the ones nobody checks:

• Site name, region and coordinates. Sites often go by two or three names locally. Write down all of them plus the region, and a dive from five years ago is still findable.
• Gas and cylinder details, not just “air” or “nitrox” — the actual O₂ percentage, cylinder size, and start/end pressure. This is what lets you calculate a real SAC rate later instead of guessing at your air consumption from memory.
• Weighting, tied to the exact exposure suit and cylinder combination. This is the single most commonly skipped field, and the one that saves the most time on a return trip.
• Conditions and a personal note — visibility, current, water temperature, and anything worth remembering about the dive itself. This is the part that turns a logbook into a record of your diving rather than a compliance document.

A field that’s easy to forget until it matters

Equipment serial numbers rarely feel urgent to record — until a regulator goes missing at customs, or an insurer asks for proof of what you owned. Recording make, model and serial number once, when you buy a piece of gear, takes under a minute. Reconstructing it after a loss does not.

What a logbook isn’t for

It’s not a decompression record and it’s not a substitute for your dive computer’s log — depth and time are estimates you copy across, not the authoritative source. It also isn’t proof of certification by itself; agencies verify certification independently, and a logbook only supports what your card already says.

FAQ

Does a digital log count the same as a paper one? Most dive centers accept either — what matters is that it’s current and consistent, not the format.

How far back do dive centers usually look? Recency matters more than total count for many activities — a large gap since your last dive can matter more than how many dives you’ve logged overall.

What if I lost my old logbook? Reconstruct what you can from memory and any surviving records (certification cards often list a few key dives), and start logging consistently going forward — a gap in history matters less than a habit going forward.

Do I need to log every single dive, even repeats at the same site? Yes, if you want an accurate dive count and gas-consumption pattern — repeated dives at a familiar site are exactly the data that shows whether your SAC rate is actually improving.

Keep every field above without carrying a pen and logbook to the surface interval: try the free Dive Log & Gas Tracker, or start a paper record built around this exact structure with Dive Log Book.