# Alert Diver vs Poseidon Reef

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.

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.

## The numbers

| Metric | Alert Diver | Poseidon Reef |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.0 (4 ratings)](https://appshunter.io/ios/app/alert-diver/id480608662/reviews)** | [3.0 (2 ratings)](https://appshunter.io/ios/app/poseidon-reef/id1581432645/reviews) |
| Number of ratings | **4** | 2 |
| Positive reviews | **25.0% of reviews** | 0.0% of reviews |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | Every 6 months | **Every 5 weeks** |
| Monetization | Free with in-app purchases | **Ad-supported** |
| Size | 92 MB | 58 MB |
| Requires iOS | **11.0** | 12.1 |
| Devices | iPhone, iPad, iPod | **iPhone, iPad, iPod, Mac** |
| Age rating | 4+ | 4+ |
| Developer | [Divers Alert Network](https://appshunter.io/developer/1482122935) | [Poseidon Diving Systems AB](https://appshunter.io/developer/567839779) |

## What reviewers say

### Alert Diver

[App page](https://appshunter.io/ios/app/alert-diver/id480608662)

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.

**Highlights:** Dive industry research, Medical information, Dive safety guidelines, Underwater photography, Dive travel guides, Marine environmental topics

**Features:** macOS Compatibility

**In-app purchases:** none


### Poseidon Reef

[App page](https://appshunter.io/ios/app/poseidon-reef/id1581432645)

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.

**Highlights:** 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

**In-app purchases:** none


## Frequently asked questions

### Is Alert Diver free?

Alert Diver is free to download, with no in-app purchases.

### Is Poseidon Reef free?

Poseidon Reef is free to download, with no in-app purchases.

### Which has better reviews, Alert Diver or Poseidon Reef?

Alert Diver is rated higher. Alert Diver averages 4.0 out of 5 from 4 ratings, while Poseidon Reef averages 3.0 from 2 ratings.

### Do Alert Diver or Poseidon Reef have ads?

Poseidon Reef shows ads; Alert Diver does not.

### Which is updated more often, Alert Diver or Poseidon Reef?

Alert Diver ships an update every 6 months, and Poseidon Reef every 5 weeks. Most recently, Alert Diver was updated on June 9, 2026 and Poseidon Reef on June 2, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*