REEFS AND DEPTHS A wide berth should be given to all charted reefs in this area. Reefs dry during the summer months when northerly winds are blowing and are covered by up to 1 metre of water when the southerly winds blow. Additionally, some of this area has not been systematically surveyed. Many depths are from old leadline surveys or from foreign government charts whose source material is unknown. Uncharted shoals and patches of coral may exist. For further details, see The Mariner’s Handbook which contains guidance on the interpretation of source data.