The human genome is about 2 meters long and tightly folded into the cell nucleus, a sphere that is 4 million times smaller than a pinhead. How do cells avoid entangling the DNA and ensure accessibility of necessary parts? Biologists study DNA folding through the detection of pairwise physical interactions along the DNA, which results in a 3-by-3 million pixel matrix. Visualized as a heatmap, thousands of local visual patterns become apparent. Studying these patterns is like trying to understand the average layout of parks while viewing countries on a world map. Biologists need to inspect these patterns for sensemaking of biological features. We have developed 3 interactive tools to explore such large datasets at different steps: (1) seamless browsing using HiGlass, (2) local pattern exploration through decomposition in HiPiler, and (3) guided navigation with Scalable Insets. I will present our tools and discuss the generalizability of the underlying concepts.