The use of multicore fibers (MCF) for sensing applications is discussed. In particular, we report on precision interferometric sensors based on strongly-coupled core MCF fusion spliced to conventional single mode fiber. To enhance the sensor performance, our MCF is designed to mode match a standard single mode optical fiber and to support specific supermodes which interfere in a predictable manner. Our MCF sensors were used for sensing strain, vibrations, and acoustic waves. They were validated in a high-fidelity aerospace test laboratory and also in real-world environments.