Pytheas also furnished information about the sea on the other side of Thule. This may be concluded from the following passages in particular:
Strabo says [i. 63]: "Thule, which Pytheas says lies six days' sail north of Brettanice, and is near to the congealed sea (πεπηγοια θαλαττα, i.e., the Polar Sea)."
Pliny [iv. 16 (30)]: "After one day's sail from Thule the frozen sea ('mare concretum') is reached, called by some 'Cronium.'"[63]
Solinus [22, 11]: "Beyond[64] Thule we meet with the sluggish and congealed sea ('pigrum et concretum mare')."
Finally we have a well-known passage in Strabo [ii. 104] which says that Pytheas asserted that in addition to having visited the whole of Britain ...
"He had also undertaken investigations concerning Thule and those regions, in which there was no longer any distinction of land or sea or air, but a mixture of the three like sea-lung, in which he says that land and sea and everything floats, and this [i.e., the mixture] binds all together, and can neither be traversed on foot nor by boat. The substance resembling lung he has seen himself, as he says; the rest he relates according to what he has heard. This is Pytheas's tale, and he adds that when he returned here, he visited the whole ocean coast of Europe from Gadeira to Tanais."
This much-disputed description of the sea beyond Thule has first passed through Polybius, who did not believe in Pytheas and tried to throw ridicule upon him. Whether Polybius obtained it directly, or at second hand through some older writer, we do not know. From him it came down to Strabo, who had as little belief in it, and was, moreover, liable to misunderstand and to be hasty in his quotations. The passage is evidently torn from its context and has been much abbreviated in order to accentuate its improbability. It is, therefore, impossible to decide what Pytheas himself said. As it has come down to us the passage is extremely obscure, and it does not even appear clearly how much Pytheas asserted that he had himself seen, and how much he had heard; whether he had only heard of the stiffened and congealed sea (the Polar Sea), while he had really seen the condition that he compared to a lung. As to the meaning of this word there have been many and very different guesses. Some have thought that a common jelly-fish may have been called a sea-lung in the Mediterranean countries at that time, in analogy to its German designation, "Meerlunge." It may also be thought that Pytheas merely wished to describe a spongy, soft mass, like an ordinary lung.[65] In both cases the description may mean a gelatinous or pulpy mass, and what Pytheas himself saw may have been the ice sludge in the sea which is formed over a great extent along the edge of the drift ice, when this has been ground to a pulp by the action of waves. The expression "can neither be traversed on foot nor by boat" is exactly applicable to this ice-sludge. If we add to this the thick fog, which is often found near drift ice, then the description that the air is also involved in the mixture, and that land and sea and everything is merged in it, will appear very graphic. But that Pytheas should have been far enough out in the sea north of Norway to have met with drift ice is scarcely credible.[66] If, on the other hand, he wintered in Norway, he may well have seen something similar on a small scale. Along the Norwegian coast, in the Skagerak, there may be ice and ice-sludge enough in the late winter, and in the fjords as well; but in that case it is probable that he would also have seen solid ice in the fjords, and would have been able to give a clearer description of the whole, which would have left no room for such misunderstandings on the part of Polybius and Strabo. It may also appear unlikely that Pytheas should not have known ice before; he must, one would think, have seen it on pools of water in the winter even in Massalia, and from the Black Sea ice was, of course, well known to the Greeks. But then it is strange that he should have given such an obscure description of such a condition, and have said that the land was also involved in the mixture; unless we are to regard the whole passage as figurative, in which case the word land may be taken as an expression for the solid as opposed to the liquid form (the sea) and the gaseous (the air).