Great Depths vs C
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Great Depths
This app transforms your iOS device into a digital depth finder. It provides comprehensive US coastal and Great Lakes coverage with live tide data and nautical charts. Navigate safely and efficiently with offline chart storage and distance calculation features.
- Digital depth readouts
- Live tide data
- NOAA RNC nautical charts
- Offline chart storage
- Distance calculation
- Automatic chart syncing
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Turn your iOS device into a digital depth finder. Great Depths offers coverage of the entire US coast, the Great Lakes, Lake Champlain and more... Know exactly where you are on the water and cruise to your port of call directly and safely. Sail with Great Depths for iPhone and iPad. Great Depths offers digital depth readouts, live tide data and NOAA RNC nautical charts in 60 bargain-priced packages. Digital depth readouts are automatically adjusted based on current tide/lake level and are updated as you move or viewed anywhere with the touch of a finger. -- The handy mileage menu calculates distance between any two points instantly. -- Purchases are automatically synced across all your iOS devices and downloaded packages are stored locally on your devices so you don’t have to rely on cell service. -- Best of all, Great Depths is FREE and never has adds! You can download the app and preview the available charts packages without spending a dime. Chart coverage includes the entire coast of the contiguous USA, the Great Lakes, Lake Champlain, the Erie, Oswego and Champlain Canals, Lake Mead, Lake Oswego, Lake Pend Oreille, Lake Okeechobee, Lake Winnebago, Franklin D. Roosevelt Lake, Lake Cayuga, Lake Seneca Lakes, Wake Island and more....
C
Access up-to-date nautical charts for global exploration and planning. Save points of interest and routes, record tracks, and view marine weather. Upgrade for offline maps, GPS, and advanced features like shaded relief and AIS.
- Free chart viewer
- Autorouting
- Personal waypoints
- Track recording
- Marine weather forecasts
- Offline map downloads
- High-resolution bathymetry
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The C-MAP® App is the perfect companion for recreational boaters and water-lovers. Available on Mobile, Tablet or PC, you’ll always be able to access the most up to date C-MAP charts, wherever in the world you are. With full features, allowing you to explore, plan and save Points of Interest and Routes from wherever you are, the C-MAP App is the perfect aid to navigation for savvy boaters. The C-MAP App Includes: - FREE Chart Viewer - Autorouting™ – find the best route to your favourite places - Personal Waypoints - Track Recording - Thousands of pre-loaded Points of Interest - Marine Weather Forecast - Weather Along the Route - Weather Overlay - Chart Personalisation - Import & Export GPX Files – share your Routes, Tracks or Waypoints with friends - Measure Distance Tool Upgrade to Premium to unlock additional features, including: - Full GPS Functionality - Offline Map Downloads - REVEAL Shaded Relief - High-Resolution Bathymetry - Custom Depth Shading - AIS & C-MAP Traffic Try before you buy… Experience C-MAP App Premium for yourself, with a free 14-day trial (3-day trial in Denmark and Sweden). The C-MAP App updates on a continual basis, ensuring the latest, most up-to-date maps are always at your fingertips. Payment will be charged to iTunes Account at confirmation of purchase. Subscription automatically renews unless auto-renew is turned off at least 24-hours before the end of the current period. Account will be charged for renewal within 24-hours prior to the end of the current period, and identify the cost of the renewal. Subscriptions may be managed by the user and auto-renewal may be turned off by going to the user's Account Settings after purchase. Links to Your Privacy Policy and Terms of Use. Any unused portion of a free trial period, if offered, will be forfeited when the user purchases a subscription to that publication, where applicable Privacy Policy: https://www.brunswick.com/dsar Terms of Service https://appchart.c-map.com/tos.html
Screenshots
Verdict
The clearest difference is rating: C at 4.5 against Great Depths's 4.2. C also leads on ratings volume (2.4K vs 12) and chart position (#115 vs unranked). Great Depths's advantage is review sentiment (70% vs 51%) and iOS requirement (8.0 vs 15.1). On price, update cadence, ads and in-app purchases there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Great Depths sells 10 one-off in-app purchases and C sells 9 in-app purchases, starting at $1.99 per month. Whichever you choose, the download price is not the number that matters.
C holds the better App Store score, 4.5 against 4.2. That said, the two scores are not equally well evidenced: C has 2.4K ratings behind it against 12, so its average is the more settled of the two. Written reviews complicate that: 70% of Great Depths's written reviews are positive against 51% of C's, so the app with the better star average is not the one people write more warmly about.
Both ship on a similar rhythm, roughly every 6 weeks. Both last shipped on November 1, 2026.
| Parameter | Great Depths | C |
|---|---|---|
| Price | Free | Free |
| Rating | 4.2 (12 ratings) | 4.5 (2.4K ratings) — better |
| Positive reviews | 70.0% of reviews — better | 51.0% of reviews |
| Number of ratings | 12 | 2.4K — better |
| Update frequency | Every 6 weeks | Every 6 weeks |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Best chart rank | — | #115 — better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 8.0 — better | 15.1 |
| Further details — not scored | ||
| Size | 19 MB | 169 MB |
| Age rating | 4+ | 4+ |
| Developer | Walk About Apps | Navico Norway AS |
Customer experience
Great Depths
C
Bugs and requests
Great Depths
Not enough reviews yet to summarise bugs or requests.
C
Reported bugs
4 issues- App crashes when trying to save tracks or routes
- Offline maps fail to download or disappear
- Depth/contour data inaccurate or not displaying properly
- Login and authentication issues preventing access
Requested features
4 requests- Add mast height/clearance feature
- Improve AIS integration and functionality
- Allow more customization of map views and data
- Provide better customer support and communication
In-app purchases
Great Depths
- Huge East Coast ChartsFree
- Midwest Florida CoastFree
- Southwest Florida CoastFree
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- Southeast Florida CoastFree
- The Chesapeake BayFree
- New Jersey Coast and The Delaware RiverFree
- Connecticut and New York CoastFree
- Maine, New Hampshire and Northern Mass.Free
- All the ChartsFree
- Lake Champlain$0.99
C
- Embark Advanced Weather$1.991 Month
- Embark Offline Maps USA$2.491 Month
- Annual Subscription14 Days trial$14.991 Year
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- Annual subscription14 Days trial$14.991 Year
- Region14 Days trial2 variants$18.991 Year
- North America14 Days trial$23.491 Year
- Maps Lakes South East USA14 Days trial$25.991 Year
- Caribbean14 Days trial$32.991 Year
- Maps USA East Coast & Bahamas14 Days trial$39.991 Year









