This zoomable treemap visualizes UK Home Office flight data from 2011, showing hierarchical relationships between destinations, suppliers, and ticket classes. Built with D3 v2 and rendered as an SVG with smooth zoom animations, the treemap uses nested rectangles sized by paid fare amounts, with color encoding categories. Users can click to zoom between hierarchy levels. The data is loaded from a CSV and transformed using d3.nest, while the custom layout function optimizes the treemap for the current zoom state, enabling fluid transitions as users navigate the data.