The Indonesian government has initiated a program for Ina Tsunami Early Warning System by the development of sea level monitoring systems including a Cable-Based Tsunameter. Seabed feature characterization is a critical part of the engineering design process as well as for the understanding of environmental impacts. This study aims to characterize the seabed morphology along the cable route plan at the Cilacap segment by analyzing the seafloor mapping and identifying of any existing hazards. A series of marine surveys for the data acquisition hydro-acoustic and geophysics was conducted by RV Baruna Jaya IV, in December 2020. The analysis and interpretation of seabed geomorphology were conducted using qualitative methods on four Blocks. Results indicate anthropogenic objects (debris, wreck, and scars), while the features of ripples, and pockmarks. Furthermore, sediment layers which are interpreted into four units from the top to bottom shows fine grained sediment towards the top. Finally, the hazard assessment denotes that there are three hazard categories (low, medium, and high), of which the highest category is located in the pockmark cluster (Block 4). The existing CBT cable route place is faced with geomorphological obstacles and environmental threats, so it’s recommended to change the route as far as 50meters.

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