Why keep a dive log, and what to write in it
Summary
A scuba dive log records what a dive computer cannot: the exposure suit worn, the lead carried, and how warm and how well weighted the diver felt. That record answers the questions dive shops, liveaboards and dive courses ask: how many dives a diver has, when the last one was, how deep they have been, and what weight and wetsuit they need. A useful log entry has six parts: date and site, maximum depth and dive time, water temperature, suit and warmth, weight and how it felt, and one note. The post is written by Eric, a recreational diver certified in 2016 and the founder of SCUBAzen. The SCUBAzen logbook is free.
A dive log makes returning after a break easier
For a diver who dives once or twice a year, the dive log is the record that carries over between trips. Before the first dive back after a break, the log shows how deep the diver has been, what conditions they were comfortable in, and what they wore last time. The author recorded wetsuit, weight and conditions on each dive, which gave him a reference point for the next trip and more confidence that he had the right gear.
A dive log turns weight and wetsuit into known numbers
The lead a diver needs and the wetsuit that keeps them warm both change from trip to trip. A weight or wetsuit calculator can estimate both, but it cannot know how warm the diver actually felt in that water or how worn a rental suit was. A logged line such as "6 kg, 5mm, 19°C (66°F), cold by the end" is the best starting point for the next dive in similar conditions. That next dive can be years away. A diver may dive cold water once and not again until a different trip several years later, by which time nobody remembers what suit they wore or whether it was warm enough. The log keeps that record so the diver does not have to.
A dive log answers dive shop questions
Dive shops ask how many dives a diver has and when they last dived, and the answer shapes what the shop suggests. Some shops ask for a refresher after about a year out of the water, and some also go by logged dives. Big Blue Diving on Koh Tao, Thailand, asks for a refresher course from divers with fewer than 20 dives who have not dived in a year, but only two check-out dives from divers with 50 or more dives who have not dived in two years. Source: Big Blue Diving, scuba refresher policy.
Some liveaboards require a minimum number of logged dives
Some dive trips will not take a diver without enough logged dives. In the Galápagos, some liveaboards require 100 logged dives, and Dive the Galápagos recommends at least 50 logged dives even outside the high season. A diver who has dived for years without logging may have the experience and no way to show it. Before booking, a diver should ask the operator what proof it accepts and whether a digital dive log counts. Source: Dive the Galápagos, experience needed to dive the Galápagos.
Dive courses count logged dives
Advanced dive training requires a minimum number of logged dives. The PADI Divemaster course requires 40 logged dives to start and 60 logged dives to certify. Dives a diver is doing now count toward those minimums once they are written down. Source: PADI, Divemaster requirements.
What to write in a dive log
A dive computer already records depth and dive time. What it cannot record is what the diver wore, what they carried, and how the dive felt, and those are the details that matter on the next trip. A useful dive log entry is short:
- Date and site, so the dive can be found again.
- Maximum depth and dive time, copied from the dive computer if the diver has one.
- Water temperature, which puts everything else in context.
- Exposure suit and warmth: cold, fine or warm.
- Weight and how it felt: light, right or heavy.
- One note: what the diver saw, or what they would change next time.
Every other field can stay blank. A short entry on every dive is worth more than a complete entry on the first three.
Why divers stop logging, and three habits that help
In the author's experience, logging lapses because of timing. The effort comes straight after the dive, and the payoff comes months later at a rental counter or a liveaboard boarding ramp. Three habits close that gap. First, log at the surface interval or the same evening, while the diver still remembers how the weight felt. Second, keep each entry to the six details above, which should take several minutes. Third, do not retype what did not change. On a dive trip, the dive shop, place, tank and suit are usually the same as the day before. In the SCUBAzen app, if the last dive was today or yesterday, the logbook fills those in, along with the weight, so the diver only adds what changed.
How the SCUBAzen logbook works
The SCUBAzen logbook is free and has no required fields, so a dive saves with whatever the diver had time to enter. Dives save without a signal and sync when the phone is back online. Photos can be added to a dive when the phone has a connection. SCUBAzen's Zenfinder wetsuit recommendation adjusts to the warmth a diver logged in similar water, and the Zenfinder logbook tab shows what the diver wore and carried on past dives near the current water temperature. SCUBAzen imports a CSV logbook export from apps such as Subsurface, MacDive, Shearwater Cloud and Diving Log, and a diver catching up a paper logbook can set each dive number by hand.
How to restart a dive log
A diver who has stopped logging should not wait to backfill every old dive. Log the next dive first, then add older dives later, starting with the most recent trip, because that is the trip a dive shop will ask about.