Highly dynamic networks face frequent topological changes. In such a network, traditional routing protocols are inefficient and even impractical, as they need to detect network topology and update locations frequently. To mitigate this problem, this paper puts forward a location-based opportunistic geographic routing (LOGR) protocol, an opportunistic packet transmission mechanism based on geographic locations. In most traditional routing protocols, the forwarding nodes are selected in advance. In the proposed protocol, the sending node does not know which is the next-hop node. Instead, the sending node broadcasts the forwarding rules and the data packet together, utilizing the broadcast nature of wireless transmission. Then, each node receiving the packet will judge whether it has the right to forward the packet, according to the preset rules. Another difference between our protocol and common protocols lies in the priority assignment of opportunistic forwarding. In common protocols, all candidate forwarding nodes are ranked in turn. In our protocol, the absolute priority method is adopted, such that any candidate receiving the packet can derive its own priority from its location information and forwarding rules, and determine the forwarding time, without knowing the information of other candidates. In this way, our protocol eliminates the need for topology detection or location update, and avoids the huge network overhead incurred in pairwise comparison of nodes for priority assignment. Therefore, unlike traditional protocols constrained by network scale and network topology, our protocol can better adapt to the frequent topology change in the highly dynamic network Experimental results show that the LOGR protocol worked effectively on the network containing fast moving nodes, and, in the same environment, the network performed much better under the LOGR protocol than under traditional routing protocols.