Scientists had suspected that the oceans were never completely smooth, even in conditions of perfect calm, but Geosat’s images made the planet look like an enormous, lumpy potato. The oceans were full of dents, humps, bulges and troughs. For a long time scientists had assumed that the water in them was spread evenly across the globe, but the map offered a different picture. Off the south coast of India, for example, the sea level was 170 metres lower than it was in the waters around Iceland. To the north of Australia, on the other hand, it rose up to form a peak eighty-five metres above the
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