Introduction
Stuck on a Reverse Wherigo geocache with three 6-digit codes and no idea where the final is? This solver calculates the GPS coordinates directly from the codes used by the Waldmeister "The Reverse Cache - beta" cartridge. Paste the three codes from the cache listing, click solve, and get the coordinates in decimal and degrees-minutes format with one-click links to Google Maps and the Geocaching map. No need to load the cartridge and walk around guessing. Everything runs in your browser.
What this tool does
- Decodes three 6-digit Reverse Cache codes into exact GPS coordinates using the Waldmeister algorithm.
- Determines the hemisphere (N/S and E/W) automatically from digit a4 of the first code.
- Selects between two coordinate assembly algorithms based on the parity of digits c2 and c5.
- Outputs coordinates in both decimal degrees (DD.ddddd) and degrees-minutes (DD MM.mmmm) formats.
- Provides direct links to Google Maps and the Geocaching.com map so you can navigate to the final immediately.
How this tool works
The solver takes three 6-digit codes labeled A, B, and C. Each code is split into six individual digits. For example, code A = 411401 splits into a1=4, a2=1, a3=1, a4=4, a5=0, a6=1.
The hemisphere is determined by digit a4. If a4 is 1, the coordinates are north and east. If a4 is 2, south and east. If a4 is 3, north and west. If a4 is 4, south and west. Any other value for a4 produces an error because the cartridge only supports these four combinations.
The algorithm selection depends on the sum of digits c2 and c5 from code C. If the sum is even, the solver uses Algorithm 1. If the sum is odd, it uses Algorithm 2. Both algorithms assemble the latitude and longitude digits from specific positions across all three codes.
Algorithm 1 assembles latitude as a3 b5 . b2 c4 a1 c5 a6 and longitude as a2 c1 c6 . b4 b1 a5 c2 b6. Algorithm 2 assembles latitude as b1 a6 . a3 c1 c4 c5 a1 and longitude as b5 c6 a5 . a2 b4 b6 c2 b2. The decimal portion is converted to minutes for the DMS output.
The tool validates that latitude degrees do not exceed 90 and longitude degrees do not exceed 180. If the codes produce an invalid coordinate, the solver returns an error message explaining which value is out of range.
How the cipher or encoding works
A Wherigo is a type of geocache that uses a cartridge file, similar to a small adventure game, loaded onto a GPS device or smartphone. The cartridge guides the player through tasks and zones to reach the cache container. Wherigo cartridges are built using the Wherigo Builder tool and played through the Wherigo Player app or compatible geocaching apps like c:geo.
The Reverse Wherigo, also called a Reverse Cache, is a specific cartridge created by the geocacher -Waldmeister- under the name "The Reverse Cache - beta." Instead of guiding the player to the cache through zones and tasks, the cartridge only shows the distance from the player's current position to the final cache. The player must move around and use the distance readings to triangulate the location. This format is popular because it works for any cache owner: the owner enters their cache coordinates into the cartridge generator, receives three 6-digit codes, and publishes those codes on their cache listing.
The three 6-digit codes encode the latitude and longitude through a digit rearrangement algorithm. The algorithm is not cryptographic. It is a fixed permutation of digits from the three codes into the latitude and longitude fields. There is no key and no randomness. Anyone with the three codes and the algorithm can compute the coordinates directly, which is what this solver does.
The cartridge itself is hosted on geocaching.com and has been downloaded hundreds of thousands of times. Cache owners generate codes using the official Reverse Cache beta cartridge page. The solver on this page implements the exact same digit permutation used by the cartridge, so the coordinates match what the cartridge would show if you walked to the final location.
For other geocaching puzzles, see the letters to numbers converter and the numbers to letters decoder for A=1 B=2 puzzles, or the Caesar cipher decoder for shift-based cryptograms.
How to use this tool
- Find the three 6-digit codes on the geocache listing page. They are usually labeled Code A, Code B, and Code C, or separated by spaces, commas, or line breaks.
- Enter each code into the corresponding input field above. You can also paste all three at once into the Code A field if they are separated by spaces or commas.
- The solver runs automatically as you type. Once all three fields contain 6 digits, the coordinates appear in the results card below.
- Review the solved coordinates in both decimal and degrees-minutes format. The card also shows which algorithm was used and how the digits were assembled.
- Click Open in Google Maps or Open in Geocaching Map to navigate directly to the final cache location. Use the Copy buttons to grab the coordinates in either format.
Real-world examples
Solving a Reverse Wherigo cache listing
A geocache listing in Germany provides three codes: 411401, 123456, and 789012. You enter them into the solver. Digit a4 is 4, so the hemisphere is south and west. The sum of c2 (8) and c5 (1) is 9, which is odd, so the solver uses Algorithm 2. The output coordinates are S 12.34567 W 78.90123 in decimal degrees. You click Open in Google Maps and the pin drops on a forest trail near the listed city. You navigate there and find the cache container within minutes.
Verifying your own Reverse Wherigo cache
You are hiding a Reverse Wherigo cache and used the Waldmeister cartridge generator to produce three codes for your chosen coordinates. Before publishing the cache listing, you want to verify that the codes produce the correct location. You paste the three codes into the solver and compare the output coordinates to your known cache location. They match exactly, confirming the codes are correct.
Solving a multi-stage cache with a Reverse Wherigo final
A multi-stage geocache has three stages that each reveal one 6-digit code. After finding all three stages, you have codes A, B, and C. You enter them into the solver and get the final coordinates. The solver shows Algorithm 1 was used because c2 + c5 is even. You copy the DMS coordinates and enter them as a new waypoint in your GPS app, then navigate to the final container.
Comparison with similar methods
| Method | Complexity | Typical use |
|---|---|---|
| Reverse Wherigo solver | O(1) fixed digit permutation | Waldmeister Reverse Cache - beta codes |
| Wherigo cartridge player | Requires walking and distance checks | Playing the cartridge as intended |
| Letters to numbers (A=1 B=2) | O(n) character mapping | Alphabet-based geocache puzzles |
| Caesar cipher decoder | O(25n) brute force | Shift cipher geocache puzzles |
Limitations or considerations
This solver only works for the Waldmeister "The Reverse Cache - beta" cartridge. Other Wherigo cartridges use different encoding schemes and will not produce correct coordinates with this tool. The solver does not play the cartridge or interact with the Wherigo Player app. It only computes the final coordinates from the three codes. If the cache owner used a modified or custom Reverse Wherigo cartridge, the algorithm may differ and the solver will produce incorrect coordinates. Always verify the solved coordinates against the cache listing and the surrounding terrain before searching. For other types of geocache puzzles, use the letters to numbers or Caesar cipher decoder tools.
Frequently asked questions
What is a Reverse Wherigo geocache?
A Reverse Wherigo is a geocache that uses the "The Reverse Cache - beta" cartridge created by -Waldmeister-. The cache owner enters their cache coordinates into a generator, which produces three 6-digit codes. The cacher loads the cartridge onto their GPS device or phone, enters the three codes, and the cartridge shows only the distance to the cache. The cacher must move around to triangulate the location. This solver computes the coordinates directly from the codes without needing to play the cartridge.
How do I find the three codes for a Reverse Wherigo cache?
The three 6-digit codes are published on the geocache listing page. They are usually labeled Code A, Code B, and Code C, or shown as three groups of six digits separated by spaces, commas, or line breaks. Some cache owners hide the codes behind a preliminary puzzle, but most list them directly in the cache description.
Does this solver work for all Wherigo cartridges?
No. This solver only implements the algorithm used by the Waldmeister "The Reverse Cache - beta" cartridge. Other Wherigo cartridges use different mechanics and encoding schemes. If the cache listing does not mention Waldmeister or The Reverse Cache, this tool will not produce correct coordinates.
Why does the solver show Algorithm 1 or Algorithm 2?
The Waldmeister cartridge uses two different digit assembly algorithms. The choice depends on the parity of digits c2 and c5 from code C. If c2 + c5 is even, Algorithm 1 is used. If the sum is odd, Algorithm 2 is used. The solver determines this automatically and displays which algorithm was applied so you can verify the calculation.
Are the solved coordinates exact?
The solver uses the exact same digit permutation as the Waldmeister cartridge, so the coordinates match what the cartridge would show at the final location. Small rounding differences may occur in the last decimal place due to floating point arithmetic, but the result is accurate to within approximately 1 meter, which is well within GPS accuracy.
Conclusion
The Reverse Wherigo solver saves you from walking around triangulating when you already have the three codes. Paste them in, get the coordinates, and navigate to the final. For other geocache puzzle types, try the letters to numbers converter or the Caesar cipher decoder.