The world-wide submarine cable network (SCN) is one of the most costly, complex, and critical components in the Internet. In this paper, we describe a measurement study of packet dynamics on SCN paths. To conduct this study we built an active probe-based measurement system that harnesses looking glass nodes in strategic locations in service provider networks to gather data from 134 SCN paths. During the 18 month period of our study, we also tracked outage reports from online sources on a weekly basis. Our main finding is that key dynamic characteristics of the SCN including latency, loss, path stability, and outages vary widely. To provide perspective, we assess the operational constancy of SCN path properties and find a wide range of behavior. To further clarify these characteristics, we report the results of a cluster analysis and find that paths separate into distinct groups where behavior is either relatively stable or highly variable. Our findings have implications for operational practices, applications that utilize these paths, and future measurement and monitoring of the SCN.