The eastern and western rows of atolls that form Central Maldives end in Kolhumadulu Atoll south of the channel Kudahuvadhoo Kandu. It is mostly rimmed by barrier reefs which are topped by islands or deep pools (vilu). There are many islands along its southern boundary. Owing to its typical atoll shape, it differs in no respect from atolls in the Pacific Ocean, save for its greater size. The length of Kolhumadulhu Atoll is 51 km. The lagoon is comparatively open, although it is studded with numerous small coral patches or shoals which are awash at low tide. The general depth is from 32 to 42 fathoms (59 to 77 m) and it is mud-bottomed at the centre. South of the atoll lies the deep Veymandoo Kandu channel which separates it from the Hadhdhunmathee Atoll.