# Poseidon Reef vs Halcyon Dive Systems

The clearest difference is rating: Halcyon Dive Systems at 5.0 against Poseidon Reef's 3.0. Halcyon Dive Systems also leads on ads (none vs shown) and ratings volume (8 vs 2). Poseidon Reef's advantage is device support (4 vs 1) and iOS requirement (12.1 vs 16.0). On price, update cadence, in-app purchases and monetization model there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Halcyon Dive Systems holds the better App Store score, 5.0 against 3.0. Both are backed by a comparable volume of ratings — 2 and 8 respectively.

Poseidon Reef ships an update every 5 weeks, Halcyon Dive Systems every 3 weeks. The most recent releases landed on November 3, 2026 and November 4, 2026 respectively.

## The numbers

| Metric | Poseidon Reef | Halcyon Dive Systems |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.0 (2 ratings)](https://appshunter.io/ios/app/poseidon-reef/id1581432645/reviews) | **[5.0 (8 ratings)](https://appshunter.io/ios/app/halcyon-dive-systems-diving/id6738069654/reviews)** |
| Number of ratings | 2 | **8** |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | No | No |
| Ads | Yes | **No** |
| Update frequency | Every 5 weeks | **Every 3 weeks** |
| Monetization | Ad-supported | Ad-supported |
| Size | 58 MB | 162 MB |
| Requires iOS | **12.1** | 16.0 |
| Devices | **iPhone, iPad, iPod, Mac** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Poseidon Diving Systems AB](https://appshunter.io/developer/567839779) | [Halcyon Dive Systems](https://appshunter.io/developer/1779189368) |

## What reviewers say

### 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


### Halcyon Dive Systems

[App page](https://appshunter.io/ios/app/halcyon-dive-systems-diving/id6738069654)

This app helps divers log, track, and share their underwater experiences. It offers integration with dive computers, personalized settings, and a community forum for connecting with other divers.

**Highlights:** Symbios integration for dive computer settings, Detailed dive logging and progress tracking, Social logbook for sharing dive stories, Connect with a global diving community, Personalized dive tips and advice, Exclusive benefits for Halcyon owners

**Features:** macOS Compatibility, Apple Wallet, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Poseidon Reef free?

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

### Is Halcyon Dive Systems free?

Halcyon Dive Systems is free to download, with no in-app purchases.

### Which has better reviews, Poseidon Reef or Halcyon Dive Systems?

Halcyon Dive Systems is rated higher. Poseidon Reef averages 3.0 out of 5 from 2 ratings, while Halcyon Dive Systems averages 5.0 from 8 ratings.

### Do Poseidon Reef or Halcyon Dive Systems have ads?

Poseidon Reef shows ads; Halcyon Dive Systems does not.

### Which is updated more often, Poseidon Reef or Halcyon Dive Systems?

Poseidon Reef ships an update every 5 weeks, and Halcyon Dive Systems every 3 weeks. Most recently, Poseidon Reef was updated on November 3, 2026 and Halcyon Dive Systems on November 4, 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.*