This paper concerns the development of a new ultrasonic waveguide and its application as an environmental sensor. Ultrasonic waves have been guided in cylindrical structures to check the health of the structures themselves. Here, our attention is turned to environmental sensing based oil such a cylindrical waveguide. To this end. the ultrasonic waveguide using all optical fibre and piezoelectric transducers is developed and demonstrated in a few promising applications: liquid leak detection, resin front and liquid evaporation monitoring sensors. The fibre waveguide affords notable advantages such as long-distance monitoring, minimum-invasive probing and cost-effectivity.