Anthropogenic activities have led to increased stress on our marine and other aquatic environments. There is a pressing need to monitor, measure, understand and mitigate causes of these pressures. This paper presents a novel optical head for monitoring and measuring marine based optical phenomena. The development and preliminary testing of the optical head were designed to detect optically active constituents in the marine and coastal environments. Potential applications may include the detection of Harmful Algal Blooms (HAB), which due to their production of toxins have deleterious effects on marine ecosystems, dissolved organic matter (DOM), oil spills, through the measurement of dissolved fluorescent petroleum compounds and turbidity, a key metric in marine and water quality measurements. Preliminary laboratory based results indicate that the optical head is well suited for measuring in-vivo Chlorophyll a (Chl a) fluorescence, turbidity, fluorescent dissolved organic matter (fDOM) and petroleum. For turbidity and in-vivo Chl a, analytical performance was benchmarked against off-the-shelf commercial sensors. The developed optical head demonstrates good analytical performance with certified reference standards and a very good agreement with the reference instrument.