Oceanic internal solitary waves at the Indonesian submarine wreckage site

On 21 April 2021 local time (20 April UTC), the Indonesian Navy submarine (KRI Nanggala-402) sank near the Lombok Strait, ～100 km north of the Bali Island (see magenta star in Fig. 1a), with 53 crew members dead. On the basis of Moderate Resolu-tion Imaging Spectroradiometer (MODIS) satellite images (Jack-son, 2007), NASA demonstrated that powerful "underwater waves" happened in the treacherous region and likely hit the ves-sel resulting in its disappearance (https://www.npr.org/2021/04/30/992496772/). Besides, NASA reported that the collapse depth of submarine KRI Nanggala-402 was ～200 m, but official reports on the local underwater waves and the voyage depth of the submar-ine were still lacking. This phenomenon was referred to as ocean-ic internal solitary waves (hereinafter ISWs). An important beha-viour of ISWs is causing large vertical displacements and down-ward currents in a short time in the ocean interior, and therefore may drag the submarine down to the collapse depth (i.e., ～200 m), where the water pressure exceeds the endurance limit of the sub-marine.