Merrick again...

A little more on Marks' involvement with the film (and the movie's fast tracking) via THIS PIECE at Hollywood Reporter:

Marks has been hired as a "world builder" to fill out the deep-sea universe in this action-adventure based on the 1954 film "20,000 Leagues Under the Sea," which was an adaptation of Jules Verne's classic novel. As the new "Leagues" moves toward preproduction, Marks has four weeks to work with McG and craft designers to expand the film's world to the scale of a tentpole extravaganza.

Four weeks!? They're hoping to move that fast?

Merrick here...

Justin Marks is reworking Bill Marsilii's script for 20,000 LEAGUES UNDER THE SEA: CAPTAIN NEMO. A while back, we heard that McG wants Will Smith for this movie (details HERE) - we don't know the status of this notion.

A Marsilii draft for this project was recently Rodney Kinged on the Internet, when word of its dopeyness was spread by THIS IESB SCRIPT REVIEW.

Remake will serve as an origin story of Nemo as he creates his warship, the Nautilus. Characters come from the Jules Verne novel and the 1954 actioner, that was the first live action film made by Walt Disney. Studio is fast-tracking the project that McG will direct.
[EDIT]
Disney hopes to make the film this year and is McG's follow up to "Terminator: Salvation."

...says THIS ARTICLE in Variety.

Marks is writer of Joel Silver's MASTER OF THE UNIVERSE reboot (a script I rather liked, even though many kinda didn't), the VOLTRON movie (as long as someone yells "I saw it! It's a lion!"...or whatever...all will be Copasetic), the not-so-awesome looking STREET FIGHTER adaptation (trailer HERE), and a GREEN ARROW movie (the SUPER MAX one).