I’m going to be lazy, and link to a post from two years ago about May day. This calendar image from a book of hours is an image of a Maying boat expedition.
The image is from British Library manuscript Additional 24098 folio 22v. It’s a sixteenth century book of hours from the Netherlands workshop of Simon Bening; the work the page is from is The Golf Book. The image shows a characteristic aristocratic Maying scene, in its depiction of a spring landscape (Bening is known for his landscapes), with green leaves, and branches of greenery in the boat. You’ll note there’s a lutenist, and a pipe player in the boat, presumably performing a Maying song or May carol. There appears to be an additional Maying party on the bridge above.
The style of the images is very similar to that of panel paintings, more “painterly” than earlier illuminated manuscripts, and typical of Bening’s workshop. The Golf Book is a partial ms. that consists of calendar images, similar to those in other Books of Hours, with an emphasis on leisure rather than seasonal labor. It is particularly well known for the miniature border images showing people playing games (like golf—this work has a calendar page showing people playing a game like golf, hence the title). You can see other images from The Golf Book here and here, in a calendar scene for June, showing jousting. Some medievalists may be particularly interested in the toy windmills, or in the spectacles visible in this self-Portrait of Bening.