I think - Colca Canyon, Peru is the deepest canyon on the Earth. check out my postHERE

Hello satishgsk !.... nice work on these fabolous places around the world !... I live in Chile and I notice some posts about Driest place on Earth "Atacama Desert" (that in fact it is !).. and huge earthquake measured at Valdivia City (9.5 Richter) :-)

Any way, I'm writing to complain a post about the Highest San Dune on earth... I really don't know how it was measured the Isaouane-n-Tifernine in Algeria.... also , What is a "dune" anyway ?... I'm doing this question because I know a sand dune formation at Nazca - Per� called "CERRO BLANCO" that has 2000 meters altitude above sea level and the "base" of the sand is at 1200 meters above sea level, so the vertical "height" of the dune could be the difference = 800 meters !!!... but that isn't the important thing :-) .. because the real matter is that you can acctually do a 1300 meters continue ride on a sandboard !!!

Here goes a link about Cerro Blanco where you can check how big is this "dune" ?...

http://www.mysteryperu.com/co_cerro_blanco.html

ALSO, you can see a VIDEO or a thrill sandboard ride of Cerro Blanco at:
http://www.alcanceaventura.com.br/images/sand-1.wmv

Cheerz
Yipero

On the subject of Mill Ends Park (World's Smallest Park), while you're in beautiful Portland, OR, also check out the world's largest city park, Forest Park. (See my "Wild in the City" post--updated today--for more details on this and other Portland parks). The world's largest park of any kind is Greenland National Park at over 80,000 square miles. I've been looking all over the place for the world's tallest structure: a radio mast in North Dakota.

This extremes thing is really cool, by the way. Keep up the good work!

Dude, what are you smoking? The entire island of North Manitou isn't 10 miles long or 5 miles wide. Lake Manitou in the center can't be 10 by 30 miles! Update your info on Google Earth!

Also, just in case you are interested, North Manitou island is in Lake Michigan, not Lake Huron.

I've been looking all over the place for the world's tallest structure: a radio mast in North Dakota.

This extremes thing is really cool, by the way. Keep up the good work!

The KVLY-TV mast (formerly the KTHI-TV mast) is a television transmitting tower in North Dakota, USA, used by Fargo station KVLY channel 11. At 2,063 ft (628.8 m), it is currently the world's tallest supported structure on land.

http://www.answers.com/topic/kvly-tv-mast

http://www.answers.com/topic/list-of-tallest-buildings-and-structures-in-the-world

Base jumping - the record is now Mera peak as described here: http://www.mounteverest.net/news.php?id=7951

Well regarding the most populated city, I tend to disagree.

Chongqing, China

Facts and figures of Chongqing
Provincial Capital Chongqing
Area in qkm 31815
Population (in 10000) 3130


That's a whooping 31.3 milion!!!

Lake Manitou is the correct lake but the island is called Manitoulin Island, which is in Lake Huron.
http://www.manitoulintourism.com/Maps%20&%20Mileage.htm