I wonder how that Sherman got turned upside down though... Artillery? 
I'm glad you asked! The gentleman who owns the property the tank is on (there are about 300 people who live on Peleliu) has a transcript from the Platoon commander of that tank unit. The tank was ordered to support the evacuation of two wounded sailors from an aviation unit. The wounded were successfully transported away, and the tank moved up to engage a couple of Japanese caves nearby. It most likely ran over an aircraft bomb that was buried as a mine. The commander of the tank was blown out of the hatch, and was the only survivor... Heavy stuff...

The Jap tunnels seem a pretty scary place to explore, considering their habit of booby-trapping everything!
There was a ton of live grenades, mess kits, shoes etc. everywhere. The worst part was seeing the flamethrower scorch marks at the entrance to the caves though... I'm still trying to sort out my emotions after seeing that...
WOW!
For me,the best part is when you found actualy ww2 video of that specific B25 plane shot down and then you explore it and found underwater! Amazing!!
I have to confess, at first I thought it was the plane in the newsreel, but the wing I saw underwater was actually from a different B-24. The two wrecks are very close, I'd estimate within about a half mile from each other.
The B-24 I saw:
http://www.pacificwrecks.com/aircraft/b-24/44-40603.htmlThe B-24 in the newsreel:
http://www.pacificwrecks.com/aircraft/b-24/44-42058.htmlMy curiosity with exploring war sites has always been: did you find any corpse (e.g. human remains like skeletons, bones)?
Are the sites well-preserved (not altered/robbed by prospectors)? I see that there are still ammunition there.
I did see some human remains. I won't go into much detail out of respect for the deceased, but needless to say it was utterly tragic to behold.
The sites themselves are extremely well preserved. With a few exceptions, imagine the war ended, and the jungle grew up. That's Peleliu. Much unexploded ordnance has been removed, but there's still a lot out there in the jungle.
Great video! Very well done, the sights help a lot too, of course 
A scuba question: what species of fish is that around the 2 minute mark? (I mean the large group in which you can also see a guy swimming around).
Thanks man! Unfortunately I'm not really positive what those big schools of fish were. I don't think they were barracuda though. Some other long-ish fish... I obviously need to work on my marine wildlife identification

Anyway, you seem to emerge in a cave around 3:15, is it under the sea? How's the air like in that pocket?
That dive was called the "Chandelier Caverns," a very well known dive in Palau. The air was at sea level, there were a few mostly submerged caverns. I got down to about 50' deep at one point on that dive. Pretty nifty though! As far as the air goes it was pretty stuffy, I preferred the air I brought with me