The Crest kayak sits at Jason's safehouse as the second safehouse vehicle beside the Enduro. It is one of the small boats that opens Leonida's water straight from home.
The official line is the same as for the Enduro: 'Switch gears and soak up the sun in an Army fatigue-tinged Dinka Enduro motorcycle or Crest Kayak.' Some guides list the two as separate items. The official wording uses 'or,' so it is not fully clear whether both wait at the safehouse at once.
Kayaking shows up elsewhere in the previews too, including in Mount Kalaga National Park, along with scuba diving and fishing.