What is in this image? Describe it as if you were explaining it to someone from the 15th century.

Behold, the picture here portrays a scene of watercrafts, but unlike any vessel you might course through the seas or rivers. These crafts, distinguished by their tri-cornered sails akin to certain heraldic pennons, glide not upon the watery deep but upon a hard and icy surface. They are mounted upon devices similar to the blades of skates worn by ice dancers, and they are propelled by the very wind that fills their sails. The sails are cleaved into several pointed sections arranged in a way so as to catch the fiercest of gusts, allowing the vessels to race across the ice with swift ardor. In the background, you would notice the unmistakable forms of mountains, and above, the heavens are adorned with clouds. This otherworldly scene presents these swift ice-gliding contraptions marked by various figures, such as the number "35", providing identity or perhaps indicating prowess in their curious form of ice-skating navigation. It is a spectacle of both ingenuity and delight, combining the artistry of sailing with the grace of ice traversing.