HYDROGRAPHY OF THE MALDIVES. 3 



The northern extremity of the Maldives (PI. 1) consists of a single line 

 of groups, Ihavandiffulu and Tiladummati flanked on the west by an isolated 

 atoll, Makunudu. Then follows the eastern chain of the central Maldive 

 basin, composed of the southern part of Miladuinmadulu, Fadiffolu, Gaha 

 Faro, North and South Male, Felidu, Wataru Reef, and Mulaku, while the 

 western chain of groups consists of North, Middle, and Southern Malosma- 

 dulu, Goifurfehendu, Ari, and North and South Nilandu. Then comes the 

 single southern row of groups (PI. 1), Kolumadulu, Haddummati, Suvadiva, 

 and Addu. 



The depth of the channel between the eastern and western chains varies 

 from five hundred and thirteen fathoms in the central part of the channel, 

 between Miladummati and North Malosmadulu, to one hundred and ninety- 

 four, the greatest depth between South Nilandu and Mulaku (PI. 1). The 

 depth of the central basin increases gradually as we go north. It is two 

 hundred and seventeen fathoms between Ari and South Male ; its northern 

 part is separated by a shallow shelf west of North Male from the deeper 

 basin to the east of Goifurfehendu, between it and Gaha Faro, where 

 the greatest depth is two hundred and fifty-eight fathoms, increasing to 

 two hundred and sixty-six, between South Malosmadulu and Fadiffolu and 

 to five hundred and thirteen fathoms between North Malosmadulu and 

 Miladummadulu. 



The depths of the channels separating the southern groups of the double 

 chain north of Kolumadulu indicate that the southern part of the central 

 plateau dips rapidly to the eastward (PI. 1). The greatest depth of Kuda- 

 huvadu Channel between Mulaku and Kolumadulu is nearly six hundred 

 and fifty fathoms, while it is only two hundred and fifty-one fathoms in 

 the channel between South Nilandu and Kolumadulu. 



The eastward dip of the central basin can be traced from Mulaku to 

 Miladummadulu from the depths of the western channels which are some- 

 what shallower than those dividing the groups of the eastern face. On the 

 western flank of the central basin the depth of the centre of the channel 

 between South Nilandu and North Nilandu is 200 fathoms. On the eastern 

 flank in the centre of South and North Wataru channels we find 253 and 

 283 fathoms. The depth of Ariyaddu Channel is 231 fathoms, that of 



