I2P is a widely used low-latency anonymous network that provides privacy to service providers, such as anonymous web services called eepSites. The large-scale discovery of eepSites allows us to grasp their size, content and popularity. In this paper, three approaches were proposed to discover eepSites: (1) running floodfill routers, (2) gathering hosts.txt files actively and (3) crawling popular portal eepSites. In our nineteen-day real-world experiments, the combination of the three methods in total discovered 1861 online eepSites covering over 80% of all eepSites in I2P network. And the coupon collector's problem was used for theoretical analysis, showing that eepSites discovery based on running floodfill routers is straightforward and efficient with low cost. Besides, the popularity and availability of eepSites were estimated and analyzed.