Some dictionaries say that maelstrom is borrowed from Danish malstrøm. I'll go with the OED, which says it's borrowed from early modern Dutch maelstrom (nowadays spelled maalstroom). Both the Danish and Dutch words are related, being composed of the words for "whirl" and "stream". Dutch malen "to grind, whirl round" is from Proto-Indo-European *melh₂- "to crush, grind".
*melh₂- possibly became Old Russian mlinŭ, blinŭ (млинъ/блинъ) "pancake" which became the diminutive blinets (блинец?), borrowed into Yiddish as בלינצע blintse, and then into English as blintz(e). Similar food-related senses are found in the English cognates meal (as in cornmeal), and mill "building for grinding grain into flour".