144 



HYDROGRAPHY. 



island and the reefs is embraced a fine roadstead, containing many 

 safe anchorages. It has two entrances, one on the north, and the 

 other on the east ; both of these are difficult and somewhat dangerous; 

 the first is the northern outlet, and the last the Astrolabe Gut, nine 

 miles in length, and two miles at its eastern entrance, but narrowing 

 down at its western end to less than half a mile, where is situated 

 the island of Mahonga with its reef, the channel turning to the north 

 and south of it through narrow passages, infested with coral-knolls. 

 In the Astrolabe Gut there is no anchorage, and the tide runs with 

 much velocity through it. Vessels should not think of taking this 

 channel late in the day, and at any time without a steady breeze or 

 trade wind, as they may be subject to long calms and head winds, and 

 if detained over night incur much risk of loss. With a steady breeze 

 and fine weather there is little or no danger. It requires a good look- 

 out from the mast-head when sailing through the Mahonga Passage, 

 to avoid the coral lumps and projections from the main reef. The 

 Pangaimotu Passage, to the left or south of Mahonga, though narrow, 

 is safe, and leads at once to the anchorage west of Pangaimotu, which 

 is the most sheltered berth in Mariner's Bay. There are several 

 northern passages through the reefs ; these are narrow and a good 

 deal obstructed with sunken patches. An examination of these 

 proved that it was impossible to make a careful and minute survey of 

 them. With a good look-out from aloft there are many places where a 

 vessel may pass through this broken reef; the two best passages, 

 however, are those near Alata Islet, and the other bearing north-north- 

 west from the anchorage at Pangaimotu. The depth of water in 

 Mariner's Bay varies ; in most places it will be found greater than 

 10 fathoms. 



The Island of Tonga at its south side has a narrow shore-reef: the 

 land rises perpendicularly from 40 to 80 feet, and gradually declines 

 towards the northern side. Towards the centre is an extensive inlet, 

 forming a shallow lagoon, some twelve miles in circumference : this, 

 with the exception of a narrow channel leading to the town of Moua, 

 is an extensive coral flat, which is dry at low water. The passage into 

 the lagoon communicates with the Astrolabe Gut, to the east of the 

 island of Pangaimotu. I mention this, as it affords facilities of getting 

 supplies from the natives of the island at a much more reasonable 

 rate than can be obtained at the anchorage. Nikualofa is the resi- 

 dence of the chief or king ; but the anchorage off it is not so conve- 



