The mental wellbeing of seafarers is particularly at risk due to isolation and demanding work conditions. Speech as a modality has proven to be well-suited for assessing mental health associated with mental wellbeing. In this work, we describe our deployment of a speech data collection platform in the noisy and isolated environment of an oil tanker and highlight the associated challenges and our learnings. We collected speech data consisting of 378 survey sessions from 25 seafarers over nine weeks. Our analysis shows that self-reported mental wellbeing measures were correlated with speech-derived features and we present initial modelling approaches. Furthermore, we demonstrate the effectiveness of audio-quality-based filtering and denoising approaches in this uncontrolled environment. Our findings encourage a more fine-grained monitoring of mental wellbeing in the maritime setting and enable future research to develop targeted interventions to improve seafarers’ mental health.