Wearing boots and riding a boat causes your feet to appear through the boat. When you sprint in the boat, it causes sprinting particles when the boat is on water 1 block deep.
MC-244989 Sprinting Particles while in a Boat
MC-247639 Shows "sprint" particles while in a boat
MC-120488 Sprint particles may be visible while the player is riding an entity and pressing the sprint keys
MC-53721 Ocelots and stray cats in minecarts / boats still try and run