Islands are useful model systems for examining human–environmental interactions. While many anthropogenic effects visible in the archaeological and paleoecological records are terrestrial in nature (e.g., clearance of tropical forests for agriculture and settlement; introduction of nonnative flora and fauna), native peoples also relied heavily on marine environments for their subsistence and livelihood. Here we use two island case studies—Palau (Micronesia) and the Lesser Antilles (Caribbean)—and approach their long-term settlement history through a “ridge-to-reef” perspective to assess the role that human activity played in land- and seascape change over deep time. In particular, we examine the entanglement of terrestrial and marine ecosystems resulting from anthropogenic effects and cultural responses to socio-environmental feedback. We suggest that on the humanized tropical islands of the Anthropocene, mangroves, near shore and littoral areas, and coral reefs were major sites of terrestrial–marine interface chronicling and modulating anthropogenic effects.