Then Lemnos grows faint and up over the horizon comes Electra's land, arcane home of Thracian rites. Here is a great and awesome divinity, and penalties decreed for unguarded tongues. No storm sent by Jupiter ever dares to strike this land with its billows; of his own accord the god himself makes the waves rough whenever he would forbid faithless sailors to touch his shores. But the priest Thyotes comes to meet the Minyae, bids them welcome to the land and shrine, and reveals their mysteries to his guests. Thus far, Samothrace, shall I, the poet, speak among the peoples; thus dismissed remain, and let us preserve the awe for the secret rites." VALERIUS FLACCUS --Argonautica 2.431-42

"[On the outward journey] ...They rounded wooded Athos and broad Pallene, and lo! the heroes, at my suggestion, put in with pleasure at hallowed Samothrace, where are performed awful, secret rites of gods, which may not be divulged by mortals; there is a great aid in these for men, especially for every kind of seafarer." "ORPHEUS" Argonautica 467-472

"But the Argonauts, they say, [ on the return voyage] set forth from the Troad and arrived at Samothrace, where they again paid their vows to the Great Gods and dedicated in the sacred precinct the bowls which are preserved there even to this day." DIODORUS 4.49 

"Those being initiated are said to be girded with purple fillets during the ceremony, and the initiates are said to be saved from danger at sea. So Odysseus, being an initiate, is said to have been saved from the storm at sea by using the veil [of Leucothia] in place of a fillet and placing the veil below his abdomen. Not only are the initiates saved from dangers at sea, but the initiate would obtain whatever he might pray to obtain. So when the Greeks at Troy were in terrible turmoil and discord, Agamemnon, being an initiate, is said to have quelled the discord by carrying the purple cloak. Thus Aristophanes too says: "But if any of you happens to have been initiated in Samothrace, now is the time to pray"; for he is saying that these mysteries have great power to save. Thus Appolonius, too, gives as the reason for the Argonauts' being initiated that, as he says, they might sail more safely." SCHOLIA -- Parisina to Apollonius Rhodius Argonautica 1.918