Geohashing

Birthstones

Geohashing

Geohashing is an outdoor recreational activity that involves using an algorithm to generate random geographic coordinates within a predefined area. Participants, known as "geohashers," then attempt to reach these coordinates, often documenting their journey and experiences.

History

Geohashing was inspired by a webcomic from xkcd, created by Randall Munroe. The concept was introduced in the comic titled "Geohashing" on May 21, 2008. The activity quickly gained popularity among fans of the comic and outdoor enthusiasts.

Algorithm

The geohashing algorithm uses the Dow Jones Industrial Average (DJIA) closing value from the previous day and combines it with the current date to generate a set of random coordinates. The formula is as follows:

1. Take the DJIA closing value from the previous day. 2. Concatenate it with the current date in the format YYYY-MM-DD. 3. Use the MD5 hash function to generate a hash from this string. 4. Convert the first 16 characters of the hash to a decimal number. 5. Normalize this number to a value between 0 and 1. 6. Multiply this value by the size of the predefined area to get the random coordinates.

Equipment

Geohashers typically use the following equipment:

• GPS device or smartphone with GPS capabilities
• Maps
• Camera for documenting the journey
• Appropriate outdoor gear depending on the terrain and weather conditions

Community

The geohashing community is active online, with participants sharing their experiences, photos, and tips on various forums and social media platforms. The official geohashing wiki serves as a central hub for documenting expeditions and providing information about the activity.

Variations

Several variations of geohashing have emerged, including:

• Globalhashing: Using a global coordinate system instead of a local one.
• Retrohashing: Attempting to reach coordinates generated for past dates.
• Speedhashing: Reaching the coordinates as quickly as possible.

Safety

Participants are encouraged to prioritize safety while geohashing. This includes:

• Informing someone about their plans and expected return time.
• Carrying necessary supplies such as water, food, and a first aid kit.
• Being aware of local laws and regulations regarding access to private property.

See also

• Geocaching
• Orienteering
• Letterboxing