CAUTIONS Shoal patches may be encountered on the banks. These patches are usually of small extent but may have considerably less water over them than charted. Mariners are advised to exercise caution accordingly. OYSTER PODS There are numerous oyster pods and lobster traps in depths less than 50m. These are marked by small Dan buoys attached to nylon lines. SABA BANK RIDGE The Saba bank is bordered in the south and east by a ridge. This ridge consists of living coral, sand and rock. At some places this is clearly visible.