We present the first monitoring study aiming to characterize the usage of the I2P network, a low-latency anonymous network based on garlic routing. We design a distributed monitoring architecture for the I2P network and show through three one-week measurement experiments the ability of the system to identify a significant number of all running applications, among web servers and file-sharing clients. Additionally, we identify 37% of published I2P applications, which turn out to be unreachable after their publication on the I2P distributed database.