I thought I'd make a note of some geographical oddities in Europe that I find interesting. These are the preponderance of Enclaves, Exclaves and the wiggly lines that are Pene-Enclaves.
Note about map links
I've tried to get the map links 'spot on' - but failed - the link google gave me does not reproduce the map I looked at - instead, the coordinates are on the left of the displayed map, so use your mouse to drag the map to the right, and you should see the right place. Sorry about that (I would have compensated by linking 'a little to the left' - but I would have had to estimate the width of your browser window).
An enclave is when you have another bit of a different country entirely inside your own. An exclave is when you have a bit if your country surrounded totally different countries. An exclave of one country is not necessarily an enclave of another, if that exclave is on a border, then it will be bordered by two different countries. A Pene-Enclave is a 'sticky out bit'. For example, imagine a peninsula. Now, instead of having the land bordered by water, imagine it bordered by a different country.
Lesotho, for example, is an entire country which is an enclave of South Africa.
Enclaves and Exclaves
I'm grouping these together, as an exclave of one country will often (but not always) be an enclave of another.
Büsingen am Hochrhein
It forms part of the Swiss customs area, and so to travel to the rest of Germany it is necessary to pass through the border control at the main Swiss/German border.
Baarle-Nassau / Baarle-Hertog
Baarle-Nassau and Baarle-Hertog (for they are the same place) is an international mess! For me, this is the ultimate example of the genre. Pedantically, Baarle Nassau is dutch, and Baarle-Hertog is Belgian.
Inside the Netherlands, there is a small area which is Belgian. Inside some of these are small areas of the Netherlands.
Near the town are several enclaves and exclaves along the border, as well as Belgium and the Netherlands both jutting Pene-enclaves into the other.
The Drummully polyp
The Drummully polyp was the Pene-Enclave mentioned in the Strangemaps article that started this collection of Enclaves, Exclaves and Pene-Enclaves. It sits on the border between the Republic of Ireland and Northern Ireland (part of The United Kingdom).
It is situated between County Monaghan and County Fermanagh, and the Civil parish is called Drummully.
Jungholz is an Austrian area, penetrating into Germany. It's very nearly an enclave of Germany, an exclave of Austria as it meets Austria at a single point, the summit of Sorgschrofen.
There are three two-country quadripoints in the world. Another is in Baarle-Hertog/Baarle-Nassau, where H1 and H2 meet (see map on linked page). The other is not well defined, but is in the Cooch Behar district of West Bengal between India and Bangladesh - and may possibly be two such points.
The Slovenia Croatia border
The border near Brezovica, well, that's just silly.
Other border regions
There are many border regions which show odd behaviour. For example, on the Hungarian/Croatian border we see this odd boundary. When the border was defined, it followed the river. Then the river, rather inconsiderately, changed course. The same phenomenon can be seen on the English/Welsh border.
Do you know any more within Europe?
What about interesting examples in the rest of the world?