Running downwind between two landmasses only to find they are the headlands of a large bay or inlet was among the greatest fears of square rig sailors. The chance of hauling the wind and tacking out to avoid potentially fatal embayment was very slim when rigs were little more efficient at beating to windward than a haystack. This fear of embayment was especially acute when navigating in uncharted waters, as were Lieutenant James Cook and the crew of Endeavour in 1770.

Running northwest before a fresh southeast trade wind, a mountain range off her port bow and a closer landmass off her starboard bow suggested that Endeavour should pass between the two if the mainland was to be favoured, as had been her habit for the six weeks since land-falling Australia at Cape Howe. Approaching the Whitsunday Islands area, the landmass to starboard soon proved to be a headland with the way ahead blocked by connecting low land, inspiring Cook to name the bay ‘Repulse Bay’ for the way its promise of embayment ‘repulsed’ him into coming to anchor to consider his options.

Before we join Endeavour for this worrying segment of her history-making voyage, Joseph Banks, the ship’s botanist, made an irrelevant but interesting entry in his journal at this time.

Apparently, their Tahitian crewmember Tupia complained of ‘swelled gums’ that he had been quietly putting up with for a couple of weeks, the surgeon immediately giving him extract of lemon in all his drinks from then on. This insight into eighteenth century medicine raises the question that if they had extract of lemon aboard, why was sauerkraut so important in avoiding scurvy?

I digress: Lieutenant Cook’s Journal describes their potential embayment in Repulse Bay in the following transcript from his journal: I have taken the liberty of editing out the letter ‘f’ where it was used in place of ‘s’ and have also removed excessive punctuation and the use of capital letters for words that have long since been expressed in lower case. I have also interspersed clarifying comments in italics. I hope purists will not be offended.

The day of potential embayment starts on page 535 of Cook’s Journal, all times being ship’s time.

2 Saturday June 1770. At noon we were about two leagues (six miles) from the main (land) and four from the islands without us (to their east). Our latitude by observation was 20° 56', and a high promontory, which I named Cape Hillsborough bore W½N distance seven miles.

The land here is diversified by mountains, hills, plains, and valleys, and seems to be well clothed with herbage and wood: the islands which lie parallel to the coast, and from five to eight or nine miles distant (seaward of the ship), are of various height and extent; scarcely any of them are more than five leagues in circumference, and many are not four miles: besides this chain of islands, which lie at a distance from the coast, there are others much less, which lie under the land, from where we saw smoke rising in different places.

We continued to steer along the shore at the distance of about two leagues, with regular soundings from nine to ten fathoms (1 fathom =1.8 metres). At sunset, the farthest point of the main bore N48W (north west) and to the northward lay some high land (he later named Cape Conway), which I took to be an island and of which the northwest point bore 41W, but not being sure of a passage I came to anchor about eight o’clock in the evening in ten fathom water with a muddy bottom.

About ten (pm), we had a tide setting to the northward and by two (am) it had fallen nine feet; after this it began to rise and the flood came back from the northward in the direction of the islands which lay out to sea; a plain indication that there was no passage to the NW. This, however, had not appeared at daybreak when we got under sail and stood to the NW.

At eight o’clock in morning we discovered low land quite across what we took for an opening, which proved to be a bay, about five or six leagues deep; upon this we hauled our wind to the eastward round the north point of the bay (Cape Conway), which at this time bore from us N.E. by N. distant four leagues.

From this point we found the land trended N by W½N with a strait or passage between it and a large island, or islands, lying parallel to it (by now Cook was looking up the Whitsunday Passage). Having the ebb tide in our favour, we stood for this passage and by noon were just within the entrance. Our latitude by observation was 20° 26’S, Cape Hillsborough bearing S by E distance ten leagues and the north point of the bay S19 W, distance four miles. This point, which I named CAPE CONWAY, lies in latitude 26° 36’S, longitude 211° 28’W and the bay which lies between this Cape and Cape Hillsborough I called REPULSE BAY.

The greatest depth of water we found in the bay was thirteen fathoms and the least eight. In all parts there was safe anchorage, and I believe that upon proper examination some good harbours would be found in it, especially at the north side within Cape Conway for just within that Cape there lie two or three small islands, which alone would shelter that side of the bay from the southerly and south easterly winds that seem to prevail here as a trade wind (in fact, the ‘three small islands’ Cook refers to are too small with too little water under their lee for anchorage).

In the afternoon, we steered through this passage, which we found to be from three to seven miles broad and eight or nine leagues (24 to 27 miles) in length. It is formed by the mainland on the west and by the islands on the east, one of which is at least five leagues in length (Whitsunday or Hook Island).

Our depth of water in running through was from twenty to five and twenty fathom with good anchorages everywhere and the whole passage may be considered as one safe harbour, exclusive of the small bays and coves which abound on each side where ships might lie as in a basin (in calling the passage a ‘safe harbour’ Cook was optimistic, it actually being very rough during strong southeast trade winds, especially against an opposing rising tide).

The land both upon the mainland and the islands is high and diversified by hill and valley, wood and lawn, with a green and pleasant appearance. On one of the islands we discovered with our glasses two men and a woman in a canoe with an outrigger, which appeared to be larger and of a construction very different from those of bark tied together at the ends, which we have seen upon other parts of the coast. We hoped that the people here had made some further advances beyond mere animal life in those that we had seen before.

At six o’clock in the evening we were nearly at the length of the north end of the (Whitsunday) passage, the north western-most point of the main in sight bearing N 54 W and the north end of the island NNE (probably Hayman Island), with an open sea between the two points.

As this passage was discovered on Whitsunday, I called it WHITSUNDAY’S PASSAGE, and I called the islands that form it CUMBERLAND ISLANDS in honour of his Royal Highness the Duke.

We kept under an easy sail, with the lead going all night, being at the distance of about three leagues from the shore and having from twenty-one to twenty-three fathoms of water.

At daybreak, we were abreast of the point, which had been the farthest in sight to the northwest the evening before, which I named CAPE GLOUCESTER (on Gloucester Island ten miles east of modern day Bowen).

As the good ship Endeavour safely clears the Whitsunday’s Passage, we exit Cook’s journal and retrospectively view that famous period in our history:

The distance north from Cape Gloucester to the Palm Isles is about 150 miles with Magnetic Island, close off Townsville, the only island en route. Seeing no offshore obstructions north of Cape Gloucester, Endeavour sailed through the night paralleling the coast at varying distances offshore.

Surprisingly, night sailing was common ship’s practice, officers and crew obviously unaware that a huge barrier reef sprawled along the Continental Shelf, its inner reefs just a few miles to starboard of their track. Under the circumstances, it was something of a miracle that Endeavour managed to maintain that policy for another 200 miles until abeam Cape Tribulation where Cook again chose to make an offing; not to avoid embayment this time, but to clear seaward of two islets sighted in the distant north – islets that are coral cays!

In an era when making sea room off unknown landmasses was common practice, it is understandable why Cook turned Endeavour offshore for the second time since Repulse Bay, but it beggars belief that the absence of swell had not alerted any of the officers to the possibility of a huge coral breakwater being to seaward.

Most were intelligent, experienced men and James Cook himself had long proven himself an exceptionally capable hydrographer, cartographer, navigator and commander. Furthermore, he welcomed input rather than rejected it so we can only presume that no one aboard had the least inkling of danger.

All things considered, slamming onto a reef in the middle of the night was a fait accompli: something that had to happen, the only thing saving Endeavour being the miracle of a light trade wind at a time of year when it normally blows the milk out of your tea.