Around the World Submerged: The Voyage of the Triton

1029 In connection with our hydrographic and oceanographic work, of which very little can be told in this report, we seized the opportunity while in Lombok Strait to obtain deep-water samples, measure the general density, and observe temperature and other characteristics of the water. One of the simplest ways of measuring density is by behavior of the ship herself, since she will be considerably lighter in denser water and heavier in less-dense water. Correlation with known constants can give us a very good measure of the actual water conditions. To this is added careful analysis of the sample itself.

Upon going deep in Lombok Strait there were two distinct layers where the temperature changed rather rapidly, and at maximum submergence Triton was some 20 tons lighter than at periscope depth. This was easily understood, for directly to the south were the cool, deep waters of the Indian Ocean, while to the north were the warmer, saltier and shallow waters of the Sunda Sea and Flores Sea.

The heavy currents reported to exist here at various depths we can also well believe, and we have measured them. The existence of these currents bears out theories regarding the meeting of the Indian Ocean and the Flores Sea, and the resulting water density changes.

1215 Sighted ship bearing 205° true, at 7000 yards. Once again, in tracking the vessel, it proved difficult at first to determine his angle on the bow because he was continually changing course. Finally, he straightened out as the others did earlier today, and came by us at a reasonable range, steady course and speed. The vessel was a small but beautifully maintained trawler type. Probably a fisherman, possibly a government vessel or even a small yacht.

1300 Through the periscope sighted ahead a ridge of water several feet high, apparently caused by the confluence of the waters sweeping down from the north through Lombok Strait and those of the Indian Ocean coming up from the south. About this time the Diving Officer [Jim Hay] was having difficulty maintaining periscope depth at ⅓ speed. ⅔ speed was ordered to give him a little more control. In spite of this, and with a slight up angle, the ship slowly drifted downward. We thought all the time this would shortly stop, when suddenly the depth gauges began to spin; depth increased to 125 feet in the space of 40 seconds. Standard speed was ordered to pull out of the involuntary dive, and we steadied out at 125 feet, shortly thereafter regaining periscope depth with an entirely new set of trim readings.

In reconstructing the incident, it would appear that a strong northerly current of less dense Indian Ocean water had been setting in to Lombok Strait for some time, but that a current from the north was also making up. This would account for the apparent ridge or “wall” of water which we had seen ahead, for the variations of the water density when we went deep not long before, and for the erratic courses of the ships we had been watching.

At the point where we experienced the sudden change in depth, it would appear that there must have been a swirling of water, perhaps a downward current, as the Indian Ocean current met the Lombok Strait current.

Nick Mabry, the Hydrographic Office representative for oceanography, confirms our hypothesis as being a probable one. It was as though we had hit a hole in the water which acted on us as a down draft would act on an aircraft. Under the circumstances, Triton’s size, tremendously strong hull and great power pretty well eliminated any danger, especially since we had tight control of the ship at all times; but the situation of a wartime submarine with a weaker hull and only battery power must have been less comfortable.

I had experienced changes in water density many times before, but never one of this magnitude, nor this suddenness. There had been wartime reports of British submarines in the Mediterranean having somewhat the same experience, and some of the hard-to-believe stories of the period laid heavy losses in “the Med” to this phenomenon.

1313 Sighted an outrigger canoe with a sail bearing 144° true. Approached and photographed same. It appeared to have a whole family aboard.

1400 With all contacts pretty well out of sight, periscope liberty was announced for those who might be interested. Approximately 75 crew members came into the conning tower to say a fond hello and sad farewell to Bah of the beauteous damsels. They will at least be able to say they have seen it.

1630 Entered the Indian Ocean. Next stop—Cape of Good Hope.

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From the Log, Wednesday, 6 April 1960: