# Slackwater — Tides & Currents — Slack water times, offline

> Offline tide and current predictions with celestial data for global stations. (iPhone/iPad app by Open Water Software LLC.)

- Source: https://appshunter.io/ios/app/slackwater-tides-and-currents/id6813654837 (this page in markdown: same URL + `.md`)
- Developer: [Open Water Software LLC](https://appshunter.io/developer/1887683238)
- Category: Weather, Navigation
- Price: Free with in-app purchases
- Rating: 5.00/5 from 1 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 26.0 · 59 MB
- Languages: American English, Danish, Dutch, Finnish, Canadian French, Scottish Gaelic, German (Germany), Irish, Italian, Japanese and 5 more
- Released: 2026-10-12
- Data updated: 2026-11-11
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/slackwater-tides-and-currents/id6813654837/reviews.md

## What is Slackwater?

The tide and currents app that works without signal. Tides for more than 5,000 stations worldwide and currents across the US and Canada, already on your phone — on the water, on the beach, in the anchorage, with no bars and nothing to load.

No spinner. No "no internet connection". You open it, and the answer is there: rising or falling, flooding or ebbing, and how long until the next high, low or slack.

And it does the part most tide apps skip. Heights are the easy half. The harder question is the current: when does the pass go slack? How hard is it running at max? Can you get through before it turns?

WORKS WHERE THERE IS NO SIGNAL
Predictions are made on your phone, not fetched. Down a dead-end road, out at the point, in an anchorage, or with the boat's electronics down — you get the same answer you would have got at the dock. The map for your area and your favourite stations stays on your phone too.

CURRENTS, NOT JUST TIDES
Slack, max flood and max ebb on one curve, with speed and direction. Drag your thumb across the week to read any moment. Paired current stations link to the tide at their reference port.

SUN, MOON AND THE TIDES THEY DRIVE
Sunrise, sunset and twilight, the moon's phase, spring and neap tides explained, and solar and lunar eclipses, for every station.

ON YOUR WRIST, HOME SCREEN AND SIRI
An Apple Watch app that works without your phone: turn the Digital Crown to move through the day. Home screen widgets for the next event and today's curve. Ask Siri for the next low tide, high tide or slack window. On iPhone and iPad, in 16 languages.

FREE, NO ACCOUNT, NO ADS
Every station and every date is free and stays free. No account, no ads, no tracking, and the app is open source.

Slackwater Premium is optional and funds development: lock screen widgets, Apple Watch complications, alerts before the tides and currents you care about, and station calendars. Choose a yearly subscription or a one-time lifetime purchase.

WHERE THE NUMBERS COME FROM
Tides for more than 5,000 stations across a hundred countries are built in, from NOAA, the Canadian Hydrographic Service, Norway's Kartverket, Toitū Te Whenua Land Information New Zealand (LINZ), Denmark's DMI, the Japan Coast Guard and the TICON-4 global tide-gauge catalogue, and checked against each station's published tidal datums wherever it has them. Currents cover the United States and Canada: more than 2,500 NOAA current stations, plus 23 Canadian passes from the Salish Sea to Haida Gwaii and Cape Breton. Canadian tide stations download their data from the Canadian Hydrographic Service once, then work offline. Seven Canadian current passes use downloaded harmonic models; the other sixteen fetch CHS predictions when you are online and keep the downloaded window for offline use. Where we cannot publish numbers we trust, the station is listed but blank instead of guessed.

Predictions are not observations — conditions vary with weather and river flow. Not for navigation.

Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Privacy Policy: https://slackwater.xyz/privacy/

## Key features

- Offline tide and current data
- Tide predictions for 5,000+ stations
- Current speed and direction
- Sunrise, sunset, and moon phase
- Apple Watch app and widgets
- Siri integration

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Premium Yearly | $7.99 | per year |

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Premium Lifetime | $69.99 | one-time |


## Is Slackwater safe?

Not enough ratings yet to assess Slackwater.

## Is Slackwater legit?

Slackwater — Tides & Currents has limited verification signals. The AppsHunter Legitimacy Score for Slackwater is 58 out of 100 points across 7 verification signals from App Store and developer data.

## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/slackwater-tides-and-currents/id6813654837/reviews.md

### 5/5 — Helped me amazingly with my regatta

*2026-10-18*

I had a sailing regatta and needed to know what the tides would be like and what to expect Slackwater was amazing with helping me know the exact timing of everything and what to expect highly recommend to all sailors alike

## Frequently asked questions about Slackwater

### Does Slackwater have ads?

No, Slackwater is ad-free. The app explicitly states it has no ads and no tracking, ensuring an uninterrupted user experience.

### How accurate are Slackwater's tide predictions?

Slackwater uses data from official sources like NOAA and the Canadian Hydrographic Service, with predictions checked against published tidal datums where available. However, it notes that predictions are not observations and conditions can vary with weather and river flow.

### Can I use Slackwater without an internet connection?

Yes, Slackwater is designed to work offline. All tide and current predictions are made on your phone, meaning you get answers even without a signal.

### What devices does Slackwater support?

Slackwater is available on iPhone, iPad, and Apple Watch. It also offers home screen widgets for quick access to information.

### What is the cost of Slackwater?

The core features of Slackwater are free to use. An optional 'Slackwater Premium' subscription is available for $7.99 per year, offering additional features like lock screen widgets and alerts.

### How often is Slackwater updated?

The latest version is 1.15.0, last updated on November 11, 2026. While specific update frequency isn't detailed, the app receives regular updates to maintain functionality and data accuracy.

### What information does Slackwater provide besides tides?

Slackwater also provides detailed current information, including slack, max flood, and max ebb speeds and directions. It also includes sunrise, sunset, twilight times, moon phases, and explanations of spring and neap tides.

### Is Slackwater suitable for navigation?

No, Slackwater explicitly states that its predictions are not for navigation. While it provides detailed data, users should rely on official navigation charts and equipment.

## Version history (last 2 releases)

### 1.15.0 — 2026-11-11

Ask for an alert in your own words, plan around the golden and blue hour, and keep your place on iPhone Duo.

· Type or dictate when you want an alert, such as "an hour before tomorrow's low" or "whenever it rises past 8 ft", and Slackwater fills in the alert for you to check. Apple's on-device model reads the sentence, so nothing leaves your phone. This needs an iPhone with Apple Intelligence.
· Every tide and current timeline has a line for setting an alert. Press and hold the moment you care about, then tap the line. One sheet makes and edits every alert.
· Alerts can be limited to daylight, the golden hour, or the blue hour, and can follow only the lower low or higher high of each day. Alerts are part of Slackwater Premium.
· A Sun card sits beside the Moon with the next sunrise or sunset and the day's daylight. The Sun sheet lists golden hour and blue hour, and tapping any time in it moves the timeline there.
· The Moon is drawn tilted the way it looks from the station.
· Folding or unfolding an iPhone Duo keeps the moment, the week, and your place in the schedule.
· Slackwater is available in Irish and Scottish Gaelic.
· New Zealand tides use harmonic constants from Toitū Te Whenua Land Information New Zealand.
· When a station's record changes, your favorites, alerts, widgets, and watch complications follow it. A station Slackwater no longer carries says so and suggests nearby replacements.
· Canadian downloads carry on in the background when you reopen the app. On online current stations, the timeline moves on into the next week and downloads it. Downloads shows whether you're online, and each online current station has one control for its expiry and updates.
· The timeline stops where your finger lifts, unless an event is within 15 minutes.
· A Help link in Settings opens Slackwater's support page.
· Current timelines tell slack from the slack window. The line is blue inside the slack window you set in Settings and yellow outside it, where the reading keeps saying Flooding or Ebbing. Only the zero instant is green and reads Slack; the comfort current defines the window, not slack. The timeline names the slack window opening, slack, and the window closing as three moments, and the comfort current in Settings steps down to Off for slack alone. Off reaches other devices once they run 1.15 too.
· Fixes: tapping an alert notification no longer crashes Slackwater when it has been in the background; the widget, Siri, and the station card agree on the next tide at places where the tide is very small.

### 1.0 — 2026-10-13

No release notes.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-11-11.*