Final answer:
Underwater volcanoes are difficult to study due to their depths, extreme pressure, and darkness, as well as the risks they pose to equipment and researchers.
Step-by-step explanation:
Underwater volcanoes are difficult to study due to several factors. First, the depths at which these volcanoes are located make it challenging to access and observe them directly. The extreme pressure and darkness at these depths also limit the use of traditional research methods. Additionally, the underwater environment poses risks to equipment and human researchers, as well as the potential disturbance of marine life surrounding the volcanoes.