Starting in the summer 2023 and peaking in late 2023, large amounts of Sargassum were observed floating off the coast of Madeira Islands, Portugal. The analysis of the samples revealed the presence of the three most common morphotypes of the two known species of pelagic Sargassum: S. natans I, S. natans VIII, and S. fluitans III. This is the first record for the subtropical eastern Atlantic Ocean for S. natans VIII and S. fluitans III. Both species were found entangled, and even though the main purpose of the study was to document the occurrence of pelagic Sargassum in the Madeira archipelago, some associated fauna were also recorded: the crab Planes minutus (Linnaeus, 1758), the amphi-Atlantic shrimps Latreutes fucorum (Fabricius, 1798) and Hippolyte coerulescens (Fabricius, 1775), and the nudibranch Scyllaea pelagica Linnaeus, 1758. The last two are new records for the Madeira archipelago.
