Wikisurfing is the act of a group of people starting on a predetermined page on Wikipedia.org (in whatever language). Their objective is to navigate through Wikipedia to another predetermined article, using only inline links on the page excluding “See Alsos”, disambiguations, and any lists (eg: list of countries, list of singers, etc). The first person to arrive on that page wins.
So for example we’d have 5 people all on the page on the Sultan Iskandar of Johor (Malaysia), who died a few days ago, all trying to click through links to navigate to Old Ephraim - and depending on your level of general knowledge you’d know that Old Ephraim was a very large grizzly bear that lived quite happily in Utah until he got shot in the head by an unwitting shepherd. You’d have to plan your strategy - you could go through the countries-america-utah route or instead try the animals-bears-grizzlys technique. It’s very hard to find a page that you really can’t find a link to, but I’m willing to bet Old Ephraim is one of them (30 minutes without success!)
There are many variations of the game, such as one where every 5 minutes you must switch computers, another where at random times you may click a link on your neighbour’s computer, or ones where you must navigate through many topics in a sequence of your choice.
An experienced wikisurfer can tell you that there are certain topics that are dead-ends and others which are self-sustaining spirals of disaster - you will be stuck in that topic once you enter it. One example of this would probably be some complex topic in hypothetical physics. Once somewhere within the topic it’s very hard to move to another. Whereas in other topics, such as sociology, would be able to link directly to the most random of articles with almost guilty relevance.
A great way to describe this situation is that it represents the depth of a topic. A topic where it would be hard to reach other unrelated topics would be seen as an in-depth and technical topic, whereas one which could easily be changed to another (such as in 5 clicks or less) would be seen as a shallow, academically unchallenging topic. The problem when trying to measure this is determining exactly which page would be used as a base-page to attempt to navigate to.