Water may be added to Earth's surface by the bombardment of large numbers of small comets, increasing free water on Earth's surface & deepening the oceans. Continental freeboard is tied to the ocean surface, because of the balance between erosion & mountain building. Addition of water will also affect continental thickness & area. I calculate the effect of increasing ocean volume on the balance between continental & oceanic area. One model also includes crustal volume growth. Significant oceanic depths are known to exist during the Archean, because sulphide deposits requiring deep oceans occur in greenstone belts. These observations prohibit the constant addition of large quantities of water (comparable to the present day ocean volume) throughout Earth history, but smaller quantities could be added. ¿ 1999 American Geophysical Union