Thucydides, History of the Peloponnesian War
Benjamin Jowett, Ed.

26. At Pylos meanwhile the Athenians continued to blockade the Lacedaemonians in the island, and the Peloponnesian forces on the mainland¹ remained in their old position. [2] The watch was harassing to the Athenians, for they were in want both of food and water; there was only one small well, which was in the acropolis, and the soldiers were commonly in the habit of scraping away the shingle on the sea-shore, and drinking such water as they could get. The Athenian garrison was crowded into a narrow space, and, their ships having no regular anchorage, the crews took their meals on land by turns; [3] one half of the army eating while the other lay at anchor in the open sea. The unexpected length of the siege was a great discouragement to them; [4] they had hoped to starve their enemies out in a few days, for they were on a desert island, and had only brackish water to drink. [5] The secret of this protracted resistance was a proclamation issued by the Lacedaemonians offering large fixed prices, and freedom if he were a Helot, to any one who would convey into the island meal, wine, cheese or any other provision suitable for a besieged place. Many braved the danger, especially the Helots; [6] they started from all points of Peloponnesus, and before daybreak bore down upon the shore of the island looking towards the open sea. They took especial care to have a strong wind in their favour, since they were less likely to be discovered by the triremes when it blew hard from the sea. [7] The blockade was then impracticable, and the crews of the boats were perfectly reckless in running them aground; for a value had been set upon them, and Lacedaemonian hoplites were waiting to receive them about the landing-places of the island. All however who ventured when the sea was calm were captured. [8] Some too dived and swam by way of the harbour, drawing after them by a cord skins containing pounded linseed and poppy-seeds mixed with honey. At first they were not found out, but afterwards watches were posted. [9] The two parties had all sorts of devices, the one determined to send in food, the other to detect them.