Haddhunmathi Atoll or Laamu Atoll is an administrative division of the Maldives. It corresponds to the natural atoll of the same name. The administrative capital is located in Fonadhoo Island.
It is mostly rimmed by barrier reefs, the broadest of which are topped by islands. There are many islands along its eastern and southern boundaries.
This atoll is quite regular excepting for the projection of the reef at its NE corner (Isdhū Muli). It closely resembles Kolhumadulhu, its neighbour further north. Owing to its typical atoll shape, it differs in no respect from atolls in the Pacific Ocean, save for its greater size. Its reefs are generally of little breadth, with no signs of vilu (deep pools), except for its eastern fringes which are covered with islands that are quite large by Maldive standards. The lagoon is comparatively open, containing scattered shoal patches; the bottom is muddy and the average depth is from 30 to 34 fathoms (55 to 62 m).
Laamu Atoll forms the southern limit of Central Maldives. Beyond the Huvadhu Kandu, the broadest channel between atolls in the Maldives, lie the southern atolls.