The etymology of St Kilda, a small archipelago west of the Outer Hebrides, and its main island Hirta, is very complex. No saint is known by the name of Kilda, and various theories have been proposed for the word's origin, which dates from the late 16th century. Haswell-Smith (2004) notes that the full name "St Kilda" first appears on a Dutch map dated 1666, and that it may have been derived from Norse ' ("sweet wellwater") or from a mistaken Dutch assumption that the spring ' was dedicated to a saint (' is a tautological placename, consisting of the Gaelic and Norse words for "well", i.e. "well well"). The origin of the Gaelic for "Hirta"—', ', or '—which long pre-dates the use of "St Kilda", is similarly open to interpretation. Watson (1926) offers the Old Irish ', a word meaning "death", possibly relating to the dangerous seas. Maclean (1977), drawing on an Icelandic saga describing an early 13th-century voyage to Ireland that mentions a visit to the islands of ', speculates that the shape of Hirta resembles a stag, "" being "stags" in Norse.