*Article* **Internal Solitary Wave Activities near the Indonesian Submarine Wreck Site Inferred from Satellite Images**

**Tongxin Wang <sup>1</sup> , Xiaodong Huang 1,2,3,\*, Wei Zhao 1,2,3, Shihao Zheng <sup>4</sup> , Yunchao Yang <sup>1</sup> and Jiwei Tian 1,2,3**


**Abstract:** In the early morning of 21 April 2021 local time, the Indonesian Navy submarine *KRI nanggala-402* crashed in the Bali Sea (BS). As internal solitary waves (ISWs) are a great threat to submarine navigation, this paper analyzes the characteristics of ISWs in the BS by surveying satellite remote sensing images collected from 12–21 April 2021. The satellite images revealed active ISWs in the BS near the submarine wreck site with crest lengths approaching 200 km. Originating from the Lombok Strait (LS), the waves travelled northwestward across the BS deep basin, passed through the submarine wreck site, and shoaled onto the continental shelf west of the Kangean Islands, during which process, the propagation speed reached 2.69 m/s in the deep basin and 0.71 m/s in the shallow water. Based on the satellite images, the wave amplitude near the wreck site was reconstructed to be 41 m, and the reconstructed underwater wave structure showed a maximum vertical velocity of 10 cm/s. Satellite images also demonstrated the near-source evidence of ISWs near the Nusa Penida sill of the LS, and their generation were estimated to be related to the southward tidal current troughs.

**Keywords:** *KRI nanggala-402* submarine wreck; Lombok Strait; Bali Sea; internal solitary waves; remote sensing images
