[linked to the article: The 1st Hinatuan Enchanted River Head Spring Exploration]

February 19, 2010

Dive #1

This is a preliminary exploration of the spring pool to acquaint the team to the topography of the dive site.

Tide graph for 02-19-2010 (All tide charts in this article are based on the Davao chart, the nearest one available). Time in: 3:54PM, out: 4:08PM

  • Surface observation: crystal clear water with moderate flow seaward.
  • Dive descent: unlimited visibility with no halocline (a halocline is the junction between clear fresh water below and the turbid sea water above)
  • At depth: At the base (26 meters) the jam of logs is noted. These offer no particular obstruction to the deeper parts of the area. The most significant finding is a strong current coming from the fissure at the bottom of the north wall.

February 20, 2010

Dive #2

This was a planned penetration dive with cave divers Bernil and Doc on side mounts and support diver Emgee on single-tank back mount. All are using compressed air in this expedition.

Tide graph for 02-20-2010. Time in: 10:25AM, out: 10:35AM

A significant amount of seawater is still present in the head spring from the previous high tide making the water look turbid. Vegetation debris is noted to swirl around in eddies all over the water surface. The halocline is at about the 20-meter level. Upon reaching the base/bottom, the dive was aborted due to equipment failure (Doc’s right- side regulator hose busted). Very strong current was again noted.

Dive #3

This is a continuation on the previous dive, albeit with slightly limited air supply and therefore a limited bottom time.

Tide graph for 02-20-2010. Time in: 11:12AM, out: 11:49AM

On the planned team configuration of Bernil #1 and Doc #2, Bernil penetrated 7 meters to a small opening 4 feet high that rapidly tapers into a very narrow fissure to the right. Doc reached 3 meters, the only point where a solid rock served as the anchor point against the strong current. With the heavy effort moving against the current, the turn-around pressures of both tanks were reached quickly. The dive was turned.

An 8mm synthetic rope left over from a previous dive was noted, tied to a log at the base, extending halfway in and tied to a 4mm rope tied to the rocky left edge of the opening at the 7-meter mark. Other than the rope, there is no solid structure in the area for pull-and-glide propulsion against the current.

Dive #4

This was a dive to the base of the head spring pool to see if there is any change in the current pattern at near the bottom of the tide graph. The dive was done by Bernil on side mounts and Emgee on back mount.

Tide graph for 02-20-2010. Time in: 11:16AM, out: 12:01PM

Dive #5

This was the final penetration dive of the expedition (the planned02/21/10dive was scratched due to failure of the available compressor).

Tide graph for 02-20-2010. Time in: 1:33PM, out: 2:13PM

This was a planned 15-minute bottom time dive down to 48 meters to stay within a comfortable decompression length of approximately 30 minutes, again using air as bottom gas and decompression gas. After the observation of the previous dives, the plan was to use the existing ropes as the pull-and-glide purchase for easy propulsion to the small opening at the 7-meter mark from the mouth/fissure.

We were also to put new 8mm ropes all the way to the 7-meter mark opening. Doc Amores is diver #1, Bernil #2. The water is crystal clear with no halocline.

The dive proceeded with no problem; the existing rope served its purpose for pull-and-glide. The team then proceeded to penetrate the small opening and was ushered in into a huge chamber with virtually zero current. The fresh water is crystal clear. The floor is loose limestone and is on a continuous slope of approximately 40 degrees from the mouth of the cave.

With the slope, we reached the target depth of 47 meters. Aside from the floor and to a lesser extent, the ceiling to a short distance forward, we could not see the other walls, attesting to the possibility that this could be a huge cavity. At this point, the dive was turned on the time of 15 minutes.

Exiting the Hinatuan Enchanted River Cave.

Coming out, it is noted that exiting the heavy current area is facilitated by grabbing the rope and positioning feet first so one can slowly ascend without risking lung overexpansion injury from sudden gradient change as Enchanted River cave will surely spit one out, literally. It is interesting to note that this mode of exit is not common in cave diving. Incorporating techniques of the dry spelunking world, this is lowering oneself upwards!

We decided to forego the task of installing a new rope to minimize risk as we were hitting the limits. The rope was stored by Bernil in a secure place at depth.

Cave diagram by Dr. Alfonso Amores, 2010

With this final penetration dive, we may just have touched the tip of the iceberg as far as Hinatuan’s Enchanted Underwater Cave is concerned. We hope to plan further explorations of the cave using special bottom and decompression gases to maximize penetration.

  1. Daylin J. Villaflor says:

    I really hope that you can really unravel the mystery beyond that last penetration dive… i’m so thrilled.. it’s like reading an adventure novel, but you left me hanging on what’s beyond the MAD chamber!!! can’t wait to know more!!!

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