# Two Links Double Pendulum vs Under the Bay

The clearest difference is iOS requirement: Under the Bay at 15.0 against Two Links Double Pendulum's 18.2. On price, update cadence, ads and in-app purchases there is nothing between them.

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

Two Links Double Pendulum ships an update every 47 months, Under the Bay every 25 months. The most recent releases landed on October 31, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | Two Links Double Pendulum | Under the Bay |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (2 ratings)](https://appshunter.io/ios/app/under-the-bay/id1641553491/reviews)** |
| Number of ratings | — | **2** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 47 months | **Every 25 months** |
| Monetization | — | Free |
| Size | 281 MB | 930 MB |
| Requires iOS | 18.2 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Eliott Radcliffe](https://appshunter.io/developer/1477487767) | [Lisa Moren](https://appshunter.io/developer/1641553493) |

## What reviewers say

### Two Links Double Pendulum

[App page](https://appshunter.io/ios/app/two-links-double-pendulum/id1625794656)

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

**In-app purchases:** none


### Under the Bay

[App page](https://appshunter.io/ios/app/under-the-bay/id1641553491)

Experience the hidden world beneath the Chesapeake Bay through augmented reality. Point your device at water to reveal stories, hear original music, and see animations that change based on live environmental data.

**Highlights:** Augmented reality underwater exploration, Live environmental data integration, Dynamic music and animation, Artist-narrated stories, Selectable scenes, Historical data playback

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Two Links Double Pendulum free?

Two Links Double Pendulum is free to download, with no in-app purchases.

### Is Under the Bay free?

Under the Bay is free to download, with no in-app purchases.

### Do Two Links Double Pendulum or Under the Bay have ads?

Neither Two Links Double Pendulum nor Under the Bay shows ads.

### Which is updated more often, Two Links Double Pendulum or Under the Bay?

Two Links Double Pendulum ships an update every 47 months, and Under the Bay every 25 months. Most recently, Two Links Double Pendulum was updated on October 31, 2026 and Under the Bay on October 30, 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.*