Most guys who are intrigued by Corregidor history have always been interested in this WWII top secret station. To them, Station CAST and Tunnel Afirm are not new subjects. As for others including the thousands of yearly visitors to the island, few even know if its existence. The day tour buses rarely make it as far east as Kindley Field and if they do, little or nothing is told to them as they pass by this tunnel.

Imagine the possible outcome to the battles of the Coral Sea and Midway if the US did not know the Japanese plans in advance. Highly classified Japanese military and diplomatic messages were received, decoded, translated and then forwarded to US brass from this facility located near Monkey Point. Is this not worthy of even passing mention during a day tour? There is much more to Corregidor than the big guns.

I won’t go into much detail on the history of this station. Detailed information is easily available from books and on Internet sites such as Corregidor.org.

Today, the remnants of Station CAST are a bit of a mystery to many. Adding to the mystery is that none of the structures are shown on any of the detailed Corregidor maps. The reason is simple, the latest map was produced in 1936 and the Navy radio project was not started until 1939. Station CAST became operational on October 17th of that year. 

Hotel guides tell me that the tunnel and area are very rarely visited. They know of no one in the tunnel for a of couple years now. Perhaps this is due in part to the tunnel being one of the more difficult ones to get in, and more importantly, to get out of. The rumour of cobras inside seems to also keep some people away. Even the surrounding area is not friendly to the occasional visitor. Trees, vines and thorny plants are everywhere. With the exception of the South Shore Road, none of the roads and paths are clear anymore.

The massive tunnel explosion on Feb.26 1945 did destroy much of the tunnel plus virtually strip the surrounding area. Photos from that time show some large antenna poles and shattered trees to be the only objects still standing. Although much was destroyed, in this trip report I will show you what remains of this important site in Corregidor history.

1945 photo of the devastated Monkey Point. Caballo Island and the coastline of Cavite are in the background.
(Photo courtesy Corregidor.org)

So where is this this tunnel actually located? Here are few maps from various publications.

Map from “Saga of a Fortress”

Map from “American Defenses of Corregidor and Manila Bay 1899-1945”

Map from “Intercept Station ‘C’ From Olongapo
through the Evacuation of Corregidor 1929-1942”

Map source unknown

The above maps from these highly regarded books all have something in common, they are all WRONG. The tunnel is actually located further north and passes under the South Shore Road.

In 1990, Don Abbott and Ed McCarthy produced a map after completing their extensive explorations. By far, this is the most accurate tunnel map of what exists today. I would recommend reading their account posted on Corregidor.org at:

http://www.corregidor.org/heritage_battalion/abbott/navytunnel.html 

The 1990 map. (Don Abbott and Ed McCarthy)

On a few occasions I have wandered around the Monkey Point area exploring and collecting GPS waypoints for each item of interest. What remains today basically encompasses the tunnel, remnants of quarters buildings and the bases of large antenna poles. To date, I have located 17 of these poles but more probably exist. This hillside must have looked like a pin cushion from the air. The handball courts, a brick/concrete oven from a field kitchen and traces of a road can still be seen also. Not much else remains unless you count broken chunks of concrete.

2011 labeled map. Although the location of each item is accurately recorded via GPS, I have no way to place the waypoints on this old map. Using reference points, this was done manually but the results are reasonably accurate.

As usual, various drawings of the actual Tunnel Afirm interior do not completely agree. I can confirm the general tunnel shape but the only object remaining inside is a mangled steel doorway. Here are some tunnel interior drawings.

Drawing from “Intercept Station ‘C’ From Olongapo through the Evacuation of Corregidor 1929-1942”. The short laterals at the far left are not drawn to scale
 

Drawing source unknown. The short (top left) lateral is missing.

Drawing from ”Day of Infamy”. (Thanks to okla for sending this to me).
Here is a link to a large readable version of the above drawing. 

http://www.pbase.com/fots2/image/134157863/original

Although this is the most detailed drawing, the tunnel section from the “Main Entry” to the lateral on the left is definitely too short. Other drawings have this shown correct. The road passes over this section of tunnel.

Driving east towards Kindley Field on the South Shore Road (sometimes called the Monkey Point Road), few people notice a little dip in the road. You have just passed over a collapsed portion of the Navy Radio Intercept tunnel between the Main entrance and the big air shaft. 

Notice the dip in the road and guardrail. This view is looking west.
 

I’ll start at the top of the 1990 map and we will work our way down to the two Handball Courts. You may find it useful to refer to that map when looking at these photos.

First is the Panama mount of Battery Levagood. It was a concrete mount for the 155mm (6.1 inch) GPF coastal defense gun. The wheels of the gun sat on the inner ring and the rear of the gun sat on the outer ring. A rail embedded in the concrete assisted in positioning.

Looking across Battery Levagood’s Panama mount.
 

Close-up view of the rail embedded in the outer ring.

This old photo shows the gun being fired as it sits on its mount.

It is less than a one minute walk to the destroyed back entrance of the tunnel. A portion of two slanted walls of the walkway can be seen here but mostly you just see chunks of broken concrete. The map shows a wooden pole which is still there. A small crater at the base of more concrete is the actual collapsed entrance. The crawl hole is long gone.

Wooden pole and chunks of concrete.
The little crater and former crawl hole is further to the left.
 

The crawl hole was here.

It is time to enter the tunnel so let’s walk over to the side entrance. Today this is the only access point to the tunnel. Walking down the road and up the concrete walkway is the easiest way to get there. 

The walkway up to the side entrance.

At the top of the steps, turn right and you will see this walled
walkway heading down into a crater at the base of the hillside.
 

On approaching the crater you will see a hole not much higher than a man’s chest at the base of the cliff. This is the entrance we will slide in today. Karl and ExO are my companions; I would not enter this tunnel alone.

Looking straight down the hole into the tunnel.

The vertical drop from the entrance is approximately five feet. Slide in and when your feet touch the leaves you are at the top of a long 45 degree downward slope. Using a rope will help a lot to get you down and back up the loose rock safely. Anyone at the bottom had better take cover from falling debris if someone is above them. This long rocky slope is the collapsed roof of the steep staircase from the side entrance down to tunnel level.

(N.B. The rope should be one hundred feet. ExO)

View up the long rocky slope from the bottom. Light from the entrance can be seen at the top. It does not look very steep in this photo but it is. Note the rope at the bottom.

I am now standing above what would have been the base of the staircase. I say “above” because the roof has collapsed and I am standing on rubble that is several feet above the original tunnel floor. This is obvious as I have to look down at the concrete arches of two short laterals that are on both sides of me. The tunnel is dry and the air is good so no problems so far.

I moved down a few feet to get this photo of the short lateral on the right.

The view further down looking into the lateral.
The rear is intact. It is empty now except for a few rocks.

The longer lateral on the left is well below the level of the debris. A slit entrance is narrow but I see no problem to prevent me from entering. After hearing and reading what people had said about this “totally destroyed” tunnel, again, I am surprised to see a mostly intact lateral. Imagine the top secret activity in here when CAST was fully operational. On the floor lies a mangled metal door frame. 

Inside this lateral is a metal door frame. You can see a hinge on the top.

Back out in the big lateral, I move forward towards the main tunnel. The amount of fallen debris has decreased so I am walking just above the tunnel floor; the concrete arch in front of me is almost at eye level now. 

Damaged tunnel roof.
 

The walking is uneven but easy. The hazard at the moment is lots of sharp rebar sticking out. Remember it is pitch black in these tunnels, camera flash photos are deceiving.

This is the end of the side lateral.
 

The main tunnel is just past the little mound of debris.

The view when standing in the main tunnel looking in the direction of the back entrance. To the left is the intersection of the main tunnel and the concrete lined lateral. The concrete lining of the main tunnel is gone and the ceiling now has a barbequed look to it.

The view when walking towards the rear entrance.

 

Further on, some of the concrete lining is still there but broken in many places. You can slide through this narrow spot into another open area but the tunnel soon ends abruptly in a full collapse. I cannot see any remnants of the rear entrance or where a crawl space noted on the 1990 map used to be.

Back at the main tunnel/lateral intersection, here is a look at what we see looking towards the main entrance. Note the bent metal sticking down from the ceiling.

Close-up view of the bent metal. 

The Don Abbott article (link up above) says this bent metal was the diesel exhaust vent, but I don’t buy that. I see two solid metal rods connected by a piece of metal. (Note the two rods at the end of it). The blast coming from the main entrance would have been from left to right in the photo. Why not a sharp bend if it is just crumpled pipe? The 90 degree bend looks like what I would expect to see if metal rods were bent, not a hollow pipe. On the surface near where this piece of metal would appear is a metal pipe. Perhaps this is why Don thinks what is down below is the remains of it. I may be wrong, what do you guys think?

The metal pipe on the surface.

Going a bit further you see some light and feel a breeze. Here is the
large airshaft. It is impossible to know how much deeper it goes.

Standing near the base of the tall shaft and looking up.

The “void” around the shaft being caused by blast pressure blowing out loose fill is quite believable.

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