How Octo helps dive theory stick
In short
Octo teaches dive theory in four steps: a short lesson with one key idea, six quiz questions that explain every answer, spaced review that brings back what you got wrong, and a 30-question practice exam for each level. Testing yourself and spacing your reviews are two of the best-documented ways to remember what you learn.
You read the chapter on pressure and it all makes sense. Two weeks later, on the boat, someone asks why the tank empties faster at 30 m (100 ft), and the answer won’t come. Reading gives you a feeling of knowing; to remember, you need to recall the answer and come back to it over time. Octo is built around those two habits.
What is in a lesson?
Each Octo lesson is built around one key idea, explained on a few short cards, and ends with three takeaways. The 62 lessons cover four levels: Open Water Diver (20), Advanced Open Water (14), Rescue Diver (12) and Divemaster (16). Diagrams show pressure, air consumption, partial pressures and the dive profile, in meters and bar or feet and psi.
| Level | Lessons | What you review |
|---|---|---|
| Open Water Diver | 20 | Gear, pressure and your body, buddy diving, problems, planning |
| Advanced Open Water | 14 | Deep diving, narcosis, navigation, night, wreck, drift, nitrox |
| Rescue Diver | 12 | Stress and panic, rescues, first aid principles, emergency plans |
| Divemaster | 16 | Physics, physiology, decompression theory, equipment, dive management |
Why do the quizzes matter more than the reading?
Quizzes matter because recalling an answer strengthens memory more than rereading it. In a classic experiment, students who were tested on a text remembered more a week later than students who studied it again (Roediger & Karpicke, 2006). Every Octo lesson ends with six questions; each answer comes with the reason why, and the wrong options are the mistakes divers really make.
Try a question from the app
where volume changes most
During an ascent, between which two depths does a flexible air space double in volume?
Show the answer
Answer D. From 10 m to the surface, absolute pressure halves (2 to 1 bar), so the volume doubles. Halving the depth doesn’t halve the absolute pressure: from 20 m to 10 m, it goes from 3 to 2 bar, and the volume grows by only half.
How does spaced review work in Octo?
Spaced review brings back the questions you missed: a missed question comes back the same day, then again at longer and longer intervals. Key safety questions come back more often. Research on distributed practice shows that spreading reviews over time beats cramming for long-term retention (Cepeda et al., 2006); why you forget dive theory explains the research. A daily goal, a streak, badges and a Home Screen widget help you keep the habit.
What does the practice exam look like?
Each level has a practice exam of 30 questions, including real-life scenarios, scored at the end, with an optional timer. Octo shows your progress from one attempt to the next and the module to review first. The questions are original practice questions written for the app, not an agency’s exam. The practice questions by level give you a sample, and our study plans for the Open Water exam and the divemaster theory exam suggest when to take it.
Your next lesson and today’s review
Short lessons, one idea per card
Every answer explained
A practice exam for each level
The Mega Quiz for club nights (Octo Pro)
What is the Mega Quiz?
The Mega Quiz is a team quiz for dive club nights, included in Octo Pro: 300 questions from Open Water to Divemaster plus marine life, dive sites and diving history; one to four teams; 10, 20 or 30 questions with a 30-second timer; and a TV mode that shows questions and answers in large type on the club screen through AirPlay. Our quiz night guide shows how to run one.
Frequently asked questions
How long does an Octo lesson take?
A few minutes: one key idea on a few cards and three takeaways, then six quiz questions with explanations. One or two lessons a day, plus your daily review, is a pace you can keep for weeks; spaced review handles the timing of everything you missed.
Can I study in meters or in feet?
Yes. Octo follows your region’s units, and you can switch between meters and bar or feet and psi in the settings. Lessons, diagrams and calculations work in both systems, so you study in the units your instructor and your dive computer use.
Does Octo replace my course materials?
No. Octo is an unofficial study companion. Your training agency’s course, your instructor and your training dives come first; Octo helps you understand and remember the theory between sessions and before your knowledge check.
Does Octo work offline?
Yes. The lessons, questions and glossary are built into the app, so you can study without a connection, on a plane or on a dive boat. Your progress stays on your iPhone, with no account and no server. Octo Pro also removes the banner ad of the free version.
