This master’s thesis aims to better understand polar ecosystems by shedding light on the photosynthetic limitations of red coralline algae. We will use a mini remotely operated vehicle (Blueye X3) with a grabber attachment to locate and sample coralline algae from Van Mijenfjorden. We will collect samples from the maximum depth we are able to find coralline algae at and use a Diving PAM fluorometer to measure photosynthetic activity. This data will be used in comparison with parallel fieldwork from mid-latitude marine environments in Norway, making Svalbard an ideal location for studying coralline algae with this approach. With their high prevalence in marine habitats, deepening our understanding of coralline algae’s role in photosynthesis under different light regimes is important for modeling their contribution to global photosynthesis and oxygen production.