Crammed into tiny ships for days or weeks at a time--not my horn of tea. Do we have any record of songs, games, or other activities they may have used to pass the time?
(Of course other pre-modern European ships weren't much more spacious, so I suppose I'd be happy to hear what, for example, sailors on Columbus's voyages might have done all day.)
I recently listed some games confirmed its existence either in archaeological and in Old Norse written sources in: I am a seven year old Viking child. What does my daily routine look like?.
Hnefatafl (the link in my previous answer is unfortunately broken now. New linked photo is uploaded by the University of Nottingham Museum, UK) is probably the most famous one (it is also even available as an android Google app!), though I'm not sure to what extent the extant rules of the game is loyal to how the Scandinavians in the Viking Ages used to play.
Dices made of bones, horns (antlers), or teeth of the animal was also the popular toy found in different archaeological sites, and the replica of the Viking Age- Medieval dice is my personal recommendation as a small souvenir of the Viking museum (it's much cheaper than the famous hammer amulet).
While AFAIK we don't have any extant score from the Viking Age, we have a fragment of the instrument (lute) from the 10th century ruin in Denmark, and among others, the art of poetry was very respected among the 'cultured' Scandinavians. Poets (skalds) used to serve the court of the chieftain and the king to commemorate the patron's deeds, and the military retinue of the magnate, i.e. Viking expedition crews of the chieftain, were the poem's primarily intended audience.
Sagas recorded in the parchment by medieval Icelanders also include many 'improvise', situational verses (lausavísur), allegedly composed not only by quasi-professional poets, but also by the ruler himself, or even by some commoners. The famous nine arts of the Vikings by Jarl Rögnvald Kari of Orkney (d. 1158), cited in the linked answer above, also belonged to this category.
The following verse is said to have been recited by King Harald hardrada of Norway, during his expedition to Denmark and on the board of his fleet:
'Lôtum vér, meðan lirlar / líneik veri sínum/ Gerðr, í Goðnarfirði,/ galdrs, akkeri halda. (We shall let the anchor hold [us] in Randersfjord while the linen-oak [WOMAN], the Gerðr <goddess> of incantation [WOMAN], lulls her husband to sleep.)' (Haraldr harðráði Sigurðarson, Lausavísur St. 4. The translation is taken from the online edition here.)
While I cannot believe the authenticity of majority of such kind of verses (many of them were probably composed by later Icelandic saga authors), it is reasonable to suppose that the Vikings actually used to recite this kind of situational poems here and there while setting out for the voyage. So, you'd perhaps have some occasional difficulty to follow the leader's wit during the voyage/ expedition if you were not so well 'versed' in such an art of poem!
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