I am currently living in Sentani, Papua, Indonesia. I teach at a school situated on a ridge sloping off Gunung Cyclops into Lake Sentani. At the bottom of the ridge there is a cave dug into it and it runs for some distance the length of the ridge (IOW, it doesn't continue straight back but after an entrance area it adjoins another long cave). That cave system is just one of several dug and used by the Japanese here to store ammo. Occasionally, one can find ordnance even today.
Our airport uses the same strip originally built by the Japs, then bombed by us, and eventually rebuilt longer and better by us.
Another ridge here is where Gen. MacArthur (and the area is known as MacArthur's Park ~~ no cakes but plenty of rain) had his "palace". That palace consisted of about 4 rooms and really was quite small. However, from that site, MacArthur could see the whole of the area to the south. It is a spectacular view.
I understand MacArthur came ashore at what is now called "Pantai Merah", Red Beach. It is in a bay on the north shore of the island of New Guinea, but is part of the province of Papua (formerly Irian Jaya) of Indonesia. At the outside of the bay, on top of yet another bridge, there is today an overgrown grassy airstrip. I've been told there is a remnant of a WWII plane there as well as other paraphernalia. The story goes that planes low on fuel could land there if they thought they didn't have enough to make it to the larger, slightly more inland strip at Sentani.
Another story relates to the first time MacArthur came ashore here. He was sitting in a small boat, in a chair, reading a newspaper and smoking a corncob pipe. There was a sailor piloting the craft and one gunner. That is all. All of a sudden a Japanese plane came over and circled around the bay. It came low and gave that boat a second look. Apparently deciding that no one of importance would be so nonchalant, it flew off. Can you imagine what that gunner and boat pilot were thinking?
One more story. The bay at Tanah Merah is rather deep even close in to shore. In one place, a dock had been built. Again, I've been told that the US forces built it to service our ships. I can well believe it. Depth finders used for fish stop around 300' deep. We haven't measured how deep it is. There is plenty of water needed by even our largest ships to get to that dock (now I don't know about width of the bay, but it seems to me that at least two or three could be there at a time). The diving around that dock's pylons is great.
We have a metal bracelet inherited from my wife’s grandfather. It bears a 1944 Australian florin, and states: “USN Milne Bay/New Guinea”. He had been on a destroyer in Pearl Harbor when it was attacked. It is not clear how he was at Milne Bay; most histories do not indicate the presence of any USN forces except possibly Seabees. He was a gunner.