This paper presents a cost-effective Unmanned Aerial Vehicle (UAV) payload, intended for coastal area remote sensing applications. The payload consists of a compact pushbroom imaging spectrometer built in-house with commercial offthe-shelf (COTS) components, and it contains navigation sensors that allow for direct georeferencing. The payload furthermore incorporates an upward-facing spectrometer, enabling direct computation of remote sensing reflectance ρRS (λ) from imaging spectrometer data in different lighting and atmospheric conditions. In contrast to existing micro-imaging spectrometer payloads, the presented UAV payload offers enhanced versatility and flexibility. While specifically tailored to coastal ocean color mapping, the payload can easily be adapted to a wide range of remote sensing applications. The presented payload has been tested in the field. The results presented in this work, show that remote sensing payloads, built with COTS components, allow retrieving of remote sensing reflectance ρRS (λ) datacubes eligible for scientific use.