This Integrated Ecosystem Programme: Southern Benguela (IEP:SB) May 2021 cruise was conducted on the Algoa Voyage 272 in May 2021. This is a long-term monitoring line conducted off the coast of Kleinsee, Namaqualand, Elands/St Helena Bay and Scarborough on the west coast of South Africa. The IEP:SB in 2013 consolidated a long-term, multi-decadal time-series (from 1951 onward) of information for this important region and has continued monitoring in the form of the IEP:SB. The programme is a multi-disciplinary, collaborative and capacity building platform undertaking relevant science, including updating technology, with the aim to develop ecosystem indicators that can be used to effectively monitor and understand the Southern Benguela. These include physical, chemical, planktonic, microbial, seabird, marine mammal, benthic and pollution (plastic) ecosystem indicators as required by ecosystem-based management regarding the following priorities: ocean warming, ocean acidification,...