Mobile ad hoc networks (MANET) and the Internet exhibit differences in their network architecture. These differences concern the various sorts of assumptions imposed not only on the structure and topology of the underlying networks, but also on communication patterns of mobile nodes in both networks. Integrating MANET and the Internet into a hybrid network is a challenging problem due to these differences. In this paper, we propose a three-layer approach that uses both Mobile IP and dynamic destination-sequenced distance vector (DSDV) to integrate these two types of networks into a hybrid environment, in order to provide MANET nodes with Internet connectivity and access to the Internet resources. Our approach is based on the use of mobile gateways as an interface between MANET and the Internet. These mobile gateways can use Mobile IP when they communicate with the Internet and DSDV when they interact with MANET. We also show the results of several simulation experiments that were conducted to study the integrated environment.