The raw 2D multichannel seismic reflection data in this project were acquired during expedition SO299/2 offshore Krakatau using a single GI Gun. The data were recorded with a 48-channel streamer. The Krakatau survey aimed to shed light on the erupted volumes of the disastrous 1883 eruption and decipher the processes leading to a damaging tsunami. The data comprise 381 line kilometers and are provided in raw format (SEG-D) and associated standardized metadata. Detailed information on the acquisition can be found in the SO299/2 cruise report (https://doi.org/10.48433/cr_so299_2). In addition, a technical report is provided with this data set.

We are grateful to the Government of the Republic of Indonesia for granting permission to work in Indonesia's Exclusive Economic Zone. Our special thanks go to BRIN (Badan Riset dan Inovasi Nasional (Indonesia)), especially Dr.-Ing. Semeidi Husrin (Head of Coastal Engineering & Disaster Mitigation) and the German Embassy in Jakarta, especially Annisa Fitria (Head of Science & Technology Division), for obtaining research and other permits and for their help around the RV SONNE port activities.The Federal Ministry of Education and Research (BMBF) funded the project under grant (03G0299TA) with extra funding and the use of equipment from GEOMAR.Further additional funding has been provided through the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 948797).