SISTEMA ODESSA - TUMBALI
(locally Abbendittan Cave)
Sitio ABBENDITTAN,
Barangay QUIBAL,
PEÑABLANCA,
CAGAYAN PROVINCE

Surveyed Length: 7650m
Surveyed To: BCRA Grade 3-5

INTRODUCTION

The acknowledged main entrance of the Odessa Cave system i s located about 1km east of the unmettaled road running through the Barangay of Abbendittan some 8.5km north of Quibal Village. The cave is known locally as Abbendittan cave. An easy walk through secondary scrub and bamboo leads to a very large depression and a large entrance at the base of an approximately 20m high cliff face.

Apart from Treasure Hunters and some local inhabitants who penetrated into the cave for a short distance, the cave was first entered for speleological purpose in November, 1990 by 5 members of Sierra Madre Outdoors Club (SMOC); Loreto Ocampo, Richard Guzman, Bimbo Mabazza, Ralph Bubut Quinan and Manoling Cepada. Their initial exploration took them some 500m into the downstream section of the cave and to part of a large high level dry passage.

Speleo Philippines 92 entered the cave in early February 1992 with a strong team of seven cavers embarking on a three day camp. One team explored and surveyed downstream, whilst the second team progressed upstream. A number of kilometers of passage were discovered and mapped, the team returning with reinforcements for a second three day camp to extend the cave to 7.65km.

CAVE DESCRIPTION

a) Entrance Length 80m

From the (then) Only known entrance, a short walking complex opens out into a large descending passage 6m wide, leading to a vast dry dome swirl chamber some 15m in diameter and about 20m high. Two basconies overlook the up and downstream section of the main river 20m below. A one meter diameter man-made hole in the floor of the swirl chamber creates a fine 13m pit landing on a mud bank of the main river passage below, overall about 12m wide and 20m high.

The pit requires a 20m rope, the present method of attachment being to four stout poles arranged in a pyramid over the hole with a secondary belay to a nearby boulder. Alternatively, two points of descent exist over the two balconies but these were not used during the exploration.

b) Downstream Length 3670m

From the large river passage below the entrance pit, the river is followed downstream for 10m until the water sinks through an impenetrable slot to re-appear 100m further down the cave. The passage continues large and dry above the stream away into a fine Swirl Chamber some 10m in diameter and about 5m high. Turning some 180 degrees to the north-west, the passage continues dry and large for a further 260m until it regains the main river at Escape Exits 1 & 2, 20m beyond Starship Enterprise, a huge dry fossil gour barrier. This gour can be by-passed by dropping down a hole in the right wall and into a small passage which leads under the gour itself. An opening on the left 100m beyond Swirl Chamber gives an alternative route back to the river via Bimbo’s Loop.

The downstream cave continues as one fine large river passage, on average 5m wide and 4m high, often out of depth. Calcite formations frequently partially block or interupt the passageway. After 300m the river divides, the majority of the flow disappearing down a small impenetrable hole in the right hand wall behind a fine series of gours, The Banawe Gours, to emerge further down the cave in The Sewer. The way on is down a continuation of the main passage into Gour Passage which carries the smaller remnants of the main river. This secondary stream also sinks in an impenetrable hole in the right hand wall 100m beyond the Banawe Gours. Its destination has not been conclusively determined. Continuing on a large dry passage, the cave opens out in the large Chandelier Mudroom, a fine chamber with massive stalactite pendants in the roof. An inlet stream, Can’t Catch the Eel, enters Chandelier Mudroom from the left and has been followed for 240m to a sump. Continuing downstream from Chandelier Mudroom, the passage is large and wide with large roof pendants, eventually sumping after 225m. About 50m back from the sump, a large dry passage bores off to the right for 70m to meet the main stream once more, The Sewer.

At this point, The Sewer can be followed back upstream for 190m to a small gour flow partly blocking the passage. In very low water conditions this gour could possibly be passed. It is assumed this water is that sinking by the Banawe Gours in the main drain. Downstream, The Sewer continues for 506m, firstly in tight wet passage, later widening out only to be completely blocked by a gour obstruction.

From the junction of The Sewer with the cut off passage back to Gour Streamway, a large initially dry high level passage bears off on downstream right, Dia’s Light. This passage contains a lake for much of its length, at times out of depth. After 290m, a smaller passage on the right is met, Python’s Retreat. Continuing up Dia’s Light for a further 170m, the lake passage is almost completely blocked by a calcite flow but a small hole in the right hand corner allows a short duck through of 1.5m. In flood conditions, this duck would not be passable. A further 85m of wet passage leads to a dry entrance some 5m wide and 3m high giving access to an overgrown river valley. This entrance to the cave is clearly an infrequently flood resurgence.

Continuing up Python’s Retreat, 370m of heavily calcited passage leads to two further large, dry, flood resurgence entrances, heavily overgrown, clearly unused as flood exits for many years.

Dia’s Light and Python’s Retreat are heavily stocked with bats, swifts and snakes due to the proximity of the three entrances.

Warning: Most parts of the downstream cave section, especially the wet sections, will flood quickly and completely in wet weather. In exceptional wet weather, dry section of the cave may also flood, in part at least. Some safety routes are possible from the main river passage, although these are not guaranteed; Escape Exits 1 and 2, Python’s Retreat and Dia’s Light (but not in exceptional circumstances).

c) Dry High Level Series Length 879m

From the base of the entrance pit , a wide mud and boulder slope to the right of the downstream passageleads up into a ver large, dry, high level passage some 10m wide and 20m high. The initial section of this passage is the location of the underground camp used during the expedition. This passage continues large for 130m until a mud and boulder pile reduces progress to a stooping hole in the left corner. There follows 730m of fine, large, dry fossil passage, on average 6m wide and 10m high, with excelent calcite decorations. The passage terminates in a small but exceptionally well decorated chamber and crystal grotto, Heaven, which completely blocked the passage and prevents further progress.

d) Upstream Length 2920m

From the base of the entrance pit, easy walking, profusely decorated upstream passage continues via a mix of dry sandbanks, paddling and wading. After about 250m, the Main Drain achives an impressive height of about 20m with some sporting climbs to unsurveyed ledges and small grottos. Shortly before a section of limited airspace in the Main Drain, a short climb to the upstream right leads to Joander’s Loop, 500m of generally muddy passage, profusely decorated with dull brown calcite, that passes over the Main Drain and finally rejoins it from the opposite side. Another Passage here, Serious Caving, is a tight, wet, miserable outer loop that is un-likely to be revisited.

Returning to the Main Drain and passing through another section of limited air space, the walking, wading and crouching continues as before until a 2m climb out of thigh deep water onto a dry gour. About 65m further upstream is a staggered crossroads with the Double Loop to the right and a ramp up to Joander’s Loop on the left. The main Drain becomes low here, less than 1m high in places, and shortly beyond the Duck Crawl, the top entrance of the Double Loop is seen on the right. A few more metres upstream a muddy bank on the left leads to the top entrance of Joander’s Loop.

The main Drain continues in its characteristics style of alternating water and mud section, still profusely decorated, until a short section leads to a sump. A shoe-stealing muddy chamber to the right here affords access to 130m of high, glutinous passage containing a trickle of water flowing parallel to the sumped Main Drain but in the opposite direction. A low unexplored stream enters from the right at the entrance to a wide chamber containing a third stream flowing from the northern side. A low arch on the left swallows the water from the three streams and leads to a short passage of deep water terminating into a sump. This is presumably the feeder of the sump at the head of the Main Drain.

Back in the wide chamber, the stream flowing from the north has not yet been explored but a dry muddy passage on the right has been pushed to a mud choke and a short passage on the left leads to a junction with yet another south-flowing stream. Downstream soon becomes impassable, but exploration upstream - along Leech Patrol - is still incomplete after 400m of miserable crawling through domestic garbage, tangled trees and other flood debris.

Warning: Much of the upstream section will flood completely and quickly in wet conditions. There are no virtually guaranteed escape routes or safe areas.

e) Wet Resurgence - Tumbali Length 100m

On the exploratory trip which located the three dry downstream flood resurgences, the team divided outside to ascertain their location. We were inform by the local people that we are in the Barangay Tumbali. SMOC members had already identified a cave at Tumbali, scheduled for exploration by the Expedition at a later date. It was thus most likely that Tumabali Cave and Odessa are one and the same or, at the very least, linked.

At the end of the second three day camp, a two man team overland from Abbendittan to Tumbali by dilapidated motor cycle to locate Tumbali Cave and to make further enquiries of the local people. The cave entrance was located, an impressive river resurgence some 4m wide and 4m high heading out on a bearing of 355 degrees, no more that 300m from the Abbendittan - Tumbali Road. The main streamway necessitates a swim well out of depth for most of its length. The main passage continues upstream for 100m until a large, ill-defined sump is meet which block further progress. The base of the walls of the terminal passage were examined by free-diving a short distance, but the way on, the main flow and actual position of the sump could not be determined. One small dry ox-bow passage exists on upstream left, leading to a short ascending tube, blocked by calcite flow.

In view of the size of the Tumbali Cave resurgence, its location in relation to the three dry downstream flood resurgences of Odessa and its geographical bearing, it is almost certain to be the downstream resurgence of the Odessa system. It is hope that the SMOC group will attempt to gain access to the passageway between the blocked downstream section of The Sewer in Odessa and the sump in Tumbali Cave, either by removing the terminal gour restriction in The Sewer or preferably by diving the Tumbali sump. In the meantime, verification that Tumbali Cave is indeed the downstream exit of the Odessa water can be carried out by dye-testing.

CONCLUSION

Sistema Odessa - Tumbali is a fine and impressive, active, flood prone, relatively shallow through river cave, providing excelent wet sport caving, superb formations and passage shapes, canals, lakes and swimming, cave diving opportunities, good photography, dry high level passages, varied fauna and five known entrances. Some exploration is still required, particularly the remainder of upstream river and the location of further entrances where the cave water sinks. Further works should also include dye or spore testing operations to clarify, confirm and prove the source and destination of cave water, particularly at the up and downstream extremities of The Sewer, the source of the water in Can’t Catch The Eel, in the Tumbali Resurgence and the various streams in the upstream section.

The Cave is acknowledge to be a true cave system, having multiple entrances and a widespread plan shape. It is currently the third longest cave in the Philippines at 7.65km with potential in the further reaches of the upstream section to exceed 8km.