Finding data items is one of the most basic services of any distributed system. It is particular challenging in ad-hoc networks, due to their inherent decentralized nature and lack of infrastructure. A data location service (DLS) provides this capability. This paper presents 3DLS, a novel density-driven data location service. 3DLS is based on performing biased walks over a density based virtual topography. 3DLS also includes an autonomic dynamic configuration mechanism for adapting the lengths of the walks, in order to ensure good performance in varying circumstances and loads. This is without any explicit knowledge of the network characteristics, such as size, mobility speed, etc. Moreover, 3DLS does not rely on geographical knowledge, its decisions are based only on local information, it does not invoke multi-hop routing, and it avoids flooding the network. The paper includes a detailed performance study of 3DLS, carried by simulations, which compares 3DLS to other known approaches....