A novel cross-cultural exploration of how maritime peoples have engaged with the sea through cosmology, spirituality, and ritual Sentient Seas offers a global perspective on maritime cultures, examining how societies across time and space have understood and interacted with the sea. Synthesizing archaeological evidence, historical documents, and ethnographic accounts, Ian McNiven explores maritime traditions from ancient civilizations in the Middle East and Mediterranean to medieval Europe and Scandinavia to contemporary Indigenous communities in the South Pacific. McNiven investigates diverse cultural practices including shipbuilding, the treatment of shipwrecks and shipwreck victims, and maritime resource use, interpreting the evidence through the perspectives of mariners who understood the seas to be sentient and capable of acting with intentionality. He introduces the concepts of "terrestrial seascapes" and "ontological switching" to illustrate how land-based shrines and votive offerings extend maritime cosmologies and maintain a liminal transition from land to sea. By bridging anthropological and archaeological research with transdisciplinary blue humanities scholarship, Sentient Seas approaches seas as spiritscapes, recontextualizing folkloric beliefs about maritime superstitions. A volume in the series Society and Ecology in Island and Coastal Archaeology, edited by Victor D. Thompson and Scott M. Fitzpatrick