Its been a long standing rumor for WDW. Have a look at
http://www.wdwmagic.com/magic2.htm
20 August 2000: Bald/Fire Mountain -- make way for Journey to the Center of the Earth???
It is almost approaching 2 years now since the rumors about Fire Mountain and Bald Mountain (see below 1998 news) started circulating. While these projects (at least Bald Mountain) definitely existed as possible projects at WDI, it looks like they may not be built for some time - if at all. These projects now join the list of great attractions never built...or maybe until a new CEO visits the WDI model shop. (Just like how Splash Mountain was green lighted by Eisner when he visited WDI model shop)
Now here comes the rumor....please note it is a rumor, and there are at least 2 other projects being looked at by Eisner - so just as with Fire/Bald Mountain - this may come to absolutely nothing.
The next possible phase of construction at MK is to be a huge expansion into a new land (41 acres of expansion behind Big Thunder Mountain), incorporating at least 1 major E ticket ride -- a copy of the awesome thrill ride mountain being built at Tokyo Disney Sea. This is WDI at their best - and what an amazing addition this would be to MK.
The following description of the Tokyo attraction from
http://www.tokyodisneysea.co.jp/english/index.html
"Mysterious Island brings to life the writings of Jules Verne, the father of modern science fiction. Guests can visit Captain Nemo's secret base where he will invite them to become members of his crew for two thrilling adventures. On one, they will plunge to the bottom of the sea and encounter shipwrecks and mysterious creatures. On the other, they will journey to the depths the earth where the only escape route lies through an active volcano."
"Journey to the Center of the Earth" is located within the volcano itself. Riders will travel downward through the volcano in "Enhanced Motion Vehicles" and encounter a large Animatronic creature.