This report analyses global trends in conventional exploration by water depth setting over 2009-2018. The cost of exploration is compared with the value of new field discoveries made in three key water depth categories: onshore; shelf (offshore wells drilled in less than 400 metres of water); and deepwater (wells drilled in water depths of over 400 metres). Deepwater delivered almost half of the more than 253 billion boe of resource found over the decade, with high costs offset by large discovery sizes and high average volumes per well. Twice as many wells were drilled in shelf plays, and finds were often commercialised faster than in the deepwater, although discovery sizes were smaller. Most discoveries were made onshore, where costs are much lower, but tough fiscal terms often limit returns. Full details are available to download in pdf and excel format.