# Secchi vs Sea Watcher

The clearest difference is update cadence: Sea Watcher at every 6 weeks against Secchi's every 7 months. Sea Watcher also leads on iOS requirement (13.0 vs 15.6). On price, ads, 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.

Secchi ships an update every 7 months, Sea Watcher every 6 weeks. The most recent releases landed on October 10, 2026 and October 9, 2026 respectively.

## The numbers

| Metric | Secchi | Sea Watcher |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 7 months | **Every 6 weeks** |
| Monetization | — | Free |
| Size | 45 MB | 124 MB |
| Requires iOS | 15.6 | **13.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [The Secchi Disk Foundation](https://appshunter.io/developer/1487320010) | [Sea Watch Foundation - The Cetacean Monitoring Unit](https://appshunter.io/developer/1815308568) |

## What reviewers say

### Secchi

[App page](https://appshunter.io/ios/app/secchi/id1524837284)

**Features:** macOS Compatibility

**In-app purchases:** none


### Sea Watcher

[App page](https://appshunter.io/ios/app/sea-watcher/id1528176810)

Log sightings of marine megafauna like whales, dolphins, and seals across UK and European waters. Identify species, record valuable data, and contribute to scientific understanding of marine life. Review your past sightings and see what others have observed.

**Highlights:** Log marine megafauna sightings, Identify whales, dolphins, seals, and more, Record sighting location and time, Contribute to marine species research, View past and recent sightings, Learn about marine species

**In-app purchases:** none


## Frequently asked questions

### Is Secchi free?

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

### Is Sea Watcher free?

Sea Watcher is free to download, with no in-app purchases.

### Do Secchi or Sea Watcher have ads?

Neither Secchi nor Sea Watcher shows ads.

### Which is updated more often, Secchi or Sea Watcher?

Secchi ships an update every 7 months, and Sea Watcher every 6 weeks. Most recently, Secchi was updated on October 10, 2026 and Sea Watcher on October 9, 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.*