Something I've never understood is when I've heard people say and books say that the Japanese were underground while attacking the US Marines on Iwo Jima. How could they attack the Marines while underground? Please explain that someone. Also, what was the exact death toll of Americans and Japanese at Iwo Jima? Thanks.

Tunnel networks, spider holes, concealed gun emplacements. They attacked out of the ground.

As for the casualties, most Japanaese soldiers fought to the death, of over 21,800 defenders, only 200 were taken prisoner.
On the victorious Allied side, there were 26,000 casualties with nearly 7,000 dead.

You can read all about the Battle of Iwo Jima at
http://en.wikipedia.org/wiki/Battle_of_Iwo_Jima

Sweet. Thanks for the replies, guys.

Iwo was brimming caves and places for the Jap defenders to hide. Think of them as "natural bunkers". A sniper could pop out of a hole in the cave, fire off a few rounds, then go back in and hide. This was one of the many factors that impacted the number of American casualties. These caves had countless places the enemy could pop in and out of. This is where the use of the flamethrower came in.

The terrain on Iwo Jima wasn't the only reason that American casualties were extremely high. Approximately one-third of all Marines killed in action in World War II were killed at Iwo Jima, making Iwo Jima the battle with the highest number of casualties in Marine Corps history. The Japanese defenders just weren't willing to give up Iwo. Why do you ask? Because Iwo Jima was considered to be part of Japan. It was their homeland. If someone invaded your home, I'm guessing you wouldn't just surrender it either. The Japanese fought to the death on every other island on the Pacific and Iwo Jima wasn't an exception.