Nauru is a single island country situated in the middle of the vast Pacific ocean, about 60 km south of
the equator, at latitude 0ø31?S and longitude 166ø 55?E (Figure 1). Its nearest neighbour is Banaba also
known as Ocean Island in the Republic of Kiribati, about 300 km to the east. Sydney is about 4000 km
to the south, Tokyo, some 4800 km to the north west and Honolulu about 4200 km to the north east.
Nauru is an ancient submerged volcano with a karstified limestone cap of coral origin about 550m
thick (Hill and Jacobson 1989), measuring 6 km long by 4 km wide with a circumference of 18 km
and a total land area of 21 km2. The central plateau forms about 80% of the island with the highest
point to 70 m above sea level. The remaining land area is composed of a flat coastal terrace measuring 300-1000 m wide and with a mean elevation of about 3m above sea level. The shallow intertidal
fringing reef measures 110-320 m in width, and sloping 45ø angle to the ocean floor to a 4000 m
depth. Dalzell & Debao (1994) estimated that the total intertidal reef area down to the 200 m isobath
measures 7.4 km2.