Routing detours raise concerns both on network security of nations and efficiency of resource consumption. Geo-optimal routing can be viewed as a long term goal of Internet routing, and a careful designed Internet together with geo-optimal routing can produce the best performance for the Internet. In this paper, we focus on some representative intercontinental circuitous paths summarized from our measurement data set. With the help of PeerDB and CAIDA, we try to find possible reasons for the detour routing and propose some suggestions to improve interconnection and routing for ISPs.