Radio galaxies have been used quite successfully as protocluster tracers. However, because they are only visible for a short period in the evolution of a massive galaxy, a significant fraction of forming clusters remains unexplored. Clustering analysis indicate that submm-selected galaxies (SMGs) reside in very massive halos, suggesting that they trace high-density environments. Conversely, SMGs have been identified as tracers of structures with more modest masses caught in highly active periods. This suggests that SMGs may be tracers of a wider range of environments beyond the progenitors of today’s rich clusters, opening a window for a more complete exploration of protoclusters. With narrow-band Lyman-alpha imaging and multi-object spectroscopy using Palomar, Keck, Magellan and Gemini telescopes we probe for galaxy overdensities in SMG environments at z~1−5. We characterize the overdensities in these regions. We also seek to study galaxy properties according to the maturity of SMG-traced protoclusters to explore the way galaxy and local environment relate to each other within the broader picture of a cosmologically-evolving large scale structure.