from Wikipedia

Tonga is located in Oceania, an archipelago in the South Pacific Ocean, directly south of Western Samoa and about two-thirds of the way from Hawaii to New Zealand. Its 169 islands, 96 of them inhabited, are divided into three main groups--Vava'u, Ha'apai, and Tongatapu--and cover an 800-kilometer (500 mi.)-long north-south line. The largest island, Tongatapu, on which the capital city of Nuku'alofa is located, covers 257 square kilometers (99 sq. mi.). Geologically the Tongan islands are of two types: most have a limestone base formed from uplifted coral formations; others consist of limestone overlaying a volcanic base.

The climate is basically subtropical with a distinct warm period (December-April), during which the temperatures rise above 32 °C (90 °F), and a cooler period (May-November), with temperatures rarely rising above 27 °C (80 °F). The temperature increases from 23 °C to 27 °C (74 °F to 80 °F), and the annual rainfall is from 1,700 to 2,970 millimeters (67 to 117 in) as one moves from Tongatapu in the south to the more northerly islands closer to the Equator. The mean daily humidity is 80%.

Geographic coordinates: 20°00′S, 175°00′W

Map references: Oceania
total: 748 km²
land: 718 km²
water: 30 km²

Area - comparative: four times the size of Washington, D.C.
Land boundaries: 0 km
Coastline: 419 km
Maritime claims:
continental shelf: 200 m depth or to the depth of exploitation
exclusive economic zone: 200 nm (370.4 km)
territorial sea: 12 nm (22.2 km)

Climate: tropical; modified by trade winds; warm season (December to May), cool season (May to December)
Terrain: most islands have limestone base formed from uplifted coral formation; others have limestone overlying volcanic base

Elevation extremes:
lowest point: Pacific Ocean 0 m
highest point: unnamed location on Kao 1,033 m
Natural resources: fish, fertile soil

Land use:
arable land: 24%
permanent crops: 43%
permanent pastures: 6%
forests and woodland: 11%
other: 16% (1993 est.)

Irrigated land: NA km²
Natural hazards: cyclones (October to April); earthquakes and volcanic activity at Fonuafo'ou (Falcon Shoal/Island) and Late'iki (Metis Shoal/Island)
Environment - current issues: deforestation results as more and more land is being cleared for agriculture and settlement; some damage to coral reefs from starfish and indiscriminate coral and shell collectors; overhunting threatens native sea turtle populations

Environment - international agreements:
party to: Biodiversity, Climate Change, Desertification, Law of the Sea, Marine Life Conservation, Nuclear Test Ban, Ozone Layer Protection, Ship Pollution signed, but not ratified: none of the selected agreements

Geography - note: archipelago of 170 islands (36 inhabited).