Alert Diver vs Poseidon Reef
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Alert Diver
Explore dive industry insights, research, and safety information. Discover underwater photography, travel destinations, and marine environmental topics. This app provides valuable content for divers and enthusiasts.
- Dive industry research
- Medical information
- Dive safety guidelines
- Underwater photography
- Dive travel guides
- Marine environmental topics
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Alert Diver magazine, the dive industry’s leading publication, features DAN’s core content of research, education, medical information and dive safety. In addition, Alert Diver showcases underwater photography, dive travel and marine environmental topics. Divers Alert Network (DAN) is a nonprofit, 501(c)(3) dive safety organization. DAN's mission is to help divers in need of emergency medical assistance and to promote dive safety through research, education, products and services. Published quarterly, Alert Diver is a benefit to members of DAN; its companion website, AlertDiver.com, is available to all. If you are a current DAN member (DAN America region), everything offered in this app is included in your membership and free to you!
Poseidon Reef
This app helps divers log, plan, and analyze their dives. It offers detailed overviews, customizable dive logs, and advanced planning for various dive types. Connect your dive computer to manage data and firmware.
- Comprehensive dive logging
- Detailed dive planning
- Support for OC and CCR dives
- Unlimited tank support
- Decompression model selection
- Dive computer connectivity
- Cloud backup and firmware updates
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Dive into the deep with Reef, the ultimate tool for every diver regardless of experience, level, or dive style. Designed to enhance and prolong your passion for diving, Reef seamlessly extends your diving experience, both before and after the actual dive. With Reef in your pocket, you're always ready to explore. Dive Log > Get a comprehensive and detailed overview of all your dives. > Easily sort and filter to find specific dives. > Import and export dives effortlessly. > Personalize dives with custom details, photos, location and more. > Engage with your dives using the interactive chart functionality. > Visualize intricate data like tank pressures, pO2, loop temperature, etc.* > Choose the data points you want to see > Zoom in on portions of the dive you are interested in Planner > Keep track of all your upcoming dives with a comprehensive overview. > Sort, filter, and organize your dive plans. > Plan for a single dive or a series of dives. > Suitable for OC (Open Circuit) and CCR (Closed Circuit Rebreather) dives. > Supports an unlimited number of tanks. > Choose between DCAP and Buhlmann decompression models. > Bailout scenario > Configure gas content Device Manager > Connect your Poseidon M28 dive computer through WiFi > View details about connected submodules. > Download, store, and back up your dives in the cloud. > Access vital service information > Monitor total dive time > Stay updated with firmware information. *Only available with Poseidon M28 dive computer
Screenshots
Verdict
The clearest difference is rating: Alert Diver at 4.0 against Poseidon Reef's 3.0. Alert Diver also leads on ads (none vs shown) and review sentiment (25% vs 0%). Poseidon Reef's advantage is update cadence (every 5 weeks vs every 6 months) and monetization model (ad-supported vs free with in-app purchases). On price, ratings volume, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
Alert Diver holds the better App Store score, 4.0 against 3.0. Both are backed by a comparable volume of ratings — 4 and 2 respectively. Written reviews point the same way: 25% of Alert Diver's written reviews are positive against 0% of Poseidon Reef's.
Alert Diver ships an update every 6 months, Poseidon Reef every 5 weeks. The most recent releases landed on June 9, 2026 and June 2, 2026 respectively.
| Parameter | Alert Diver | Poseidon Reef |
|---|---|---|
| Price | Free | Free |
| Rating | 4.0 (4 ratings) — better | 3.0 (2 ratings) |
| Positive reviews | 25.0% of reviews — better | 0.0% of reviews |
| Number of ratings | 4 — better | 2 |
| Update frequency | Every 6 months | Every 5 weeks — better |
| Ads | No — better | Yes |
| In-app purchases | No | No |
| Monetization | Free with in-app purchases | Ad-supported — better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod, Mac — better |
| Requires iOS | 11.0 — better | 12.1 |
| Further details — not scored | ||
| Size | 92 MB | 58 MB |
| Age rating | 4+ | 4+ |
| Developer | Divers Alert Network | Poseidon Diving Systems AB |
Customer experience
Alert Diver
Poseidon Reef
In-app purchases
Alert Diver
No in-app purchases
Poseidon Reef
No in-app purchases
Questions
Is Alert Diver free?
Is Poseidon Reef free?
Which has better reviews, Alert Diver or Poseidon Reef?
Do Alert Diver or Poseidon Reef have ads?
Which is updated more often, Alert Diver or Poseidon Reef?
Other comparisons
