Upon reaching the lagoon we found it to be in reality a sort of bay in the north bank of the river, some five and a half miles long by about three and three-quarter miles wide, with an island in the centre of it occupying so large an extent of its area that at one spot the creek behind was barely wide enough to allow the passage of a vessel of moderate tonnage.  The eastern extremity of this creek, however, widened out until it presented a sheet of water some two miles long by about a mile and a half in width, with a depth of water ranging from two to three fathoms.  Furthermore, the island itself and the adjacent banks of the river were thickly wooded, affording perfect concealment, behind which half a dozen slavers might lurk undetected; and altogether it wore, as seen from the river, the aspect of an exceedingly promising spot.  We therefore lowered the boats' sails, unshipped their masts, and, keeping a bright look-out all round us, pulled warily into the lagoon at its eastern extremity.