# Poseidon Reef vs Mares App

The clearest difference is review sentiment: Mares App at 47% against Poseidon Reef's 0%. Mares App also leads on rating (4.5 vs 3.0) and ads (none vs shown). Poseidon Reef's advantage is in-app purchases (none vs 8) and iOS requirement (12.1 vs 16.6). On price, update cadence and device support there is nothing between them.

Both are free to download. Mares App sells 8 in-app purchases, starting at $2.99 per month. Poseidon Reef asks for nothing beyond the download.

Mares App holds the better App Store score, 4.5 against 3.0. That said, the two scores are not equally well evidenced: Mares App has 183 ratings behind it against 2, so its average is the more settled of the two. Written reviews point the same way: 0% of Poseidon Reef's written reviews are positive against 47% of Mares App's.

Poseidon Reef ships an update every 5 weeks, Mares App every 3 weeks. The most recent releases landed on June 2, 2026 and September 26, 2026 respectively.

## The numbers

| Metric | Poseidon Reef | Mares App |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.0 (2 ratings)](https://appshunter.io/ios/app/poseidon-reef/id1581432645/reviews) | **[4.5 (183 ratings)](https://appshunter.io/ios/app/mares-app/id1625641063/reviews)** |
| Number of ratings | 2 | **183** |
| Positive reviews | 0.0% of reviews | **47.5% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 5 weeks | **Every 3 weeks** |
| Monetization | **Ad-supported** | Free with in-app purchases |
| Size | 58 MB | 247 MB |
| Requires iOS | **12.1** | 16.6 |
| Devices | **iPhone, iPad, iPod, Mac** | iPhone, iPad, Apple Watch |
| Age rating | 4+ | 4+ |
| Developer | [Poseidon Diving Systems AB](https://appshunter.io/developer/567839779) | [Head Watersports S.p.A.](https://appshunter.io/developer/1193522423) |

## 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


### Mares App

[App page](https://appshunter.io/ios/app/mares-app/id1625641063)

Transform your Apple Watch Ultra into a dive computer, recording dives directly on your wrist. Log scuba, freediving, and technical dives, manage dive sites, and track underwater wildlife sightings. Share your adventures with dive buddies and keep your equipment details organized.

**Highlights:** Apple Watch Ultra dive computer integration, Digital dive logbook, Dive site database and management, Underwater wildlife tracking, Dive buddy sharing, Dive equipment management, Firmware updates

**Features:** macOS Compatibility, Family Sharing, Apple Watch app, Vision Pro support

**In-app purchases (8)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Snorkel Only | $2.99 | per month |
| Full Featured Month (Housing Only) | $6.99 | per month |
| Full Featured Month (Ultra Only) | $6.99 | per month |
| MARES Fully Featured Monthly | $8.99 | per month |
| Full Featured Yearly (Housing Only) | $49.99 | per year |
| Full Featured Yearly (Ultra Only) | $49.99 | per year |
| MARES Fully Featured Yearly | $69.99 | per year |
| MARES Fully Featured Yearly Family | $119.99 | per year |


## Frequently asked questions

### Is Poseidon Reef free?

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

### Is Mares App free?

Mares App is free to download, with in-app purchases available.

### Which has better reviews, Poseidon Reef or Mares App?

Mares App is rated higher. Poseidon Reef averages 3.0 out of 5 from 2 ratings, while Mares App averages 4.5 from 183 ratings.

### Do Poseidon Reef or Mares App have ads?

Poseidon Reef shows ads; Mares App does not.

### Which is updated more often, Poseidon Reef or Mares App?

Poseidon Reef ships an update every 5 weeks, and Mares App every 3 weeks. Most recently, Poseidon Reef was updated on June 2, 2026 and Mares App on September 26, 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.*