The Hardy Saddle is a mount-summoning item. When used, it summons a Turtle Mount that can swim and has increased movement speed in liquids (31 mph maximum), but reduced movement speed (10 mph maximum) and jump reach (2.48 tiles maximum) on land. It can be found in Golden Crates with a 9.33*7/75 (9.33%) chance, and in Titanium Crates with a 6.53*49/750 (6.53%) chance.
The Lava Shark Mount may be a preferable alternative for this purpose, because it is much faster and its summoning item is slightly more common.
The player can fly using the Turtle Mount and the Bottomless Water Bucket. By constantly placing water above the player and swimming upward while riding the Turtle Mount, the player can move through the sky, allowing for easy access to Floating Islands and Floating Lakes.
The Turtle Mount is also very useful for placing down blocks in a straight line. As long as the player has the Brick Layer equipped, the Turtle Mount's constant slow speed allows the player to consistently place blocks in a straight line without moving the cursor.
Despite its name, the Turtle Mount resembles a tortoise.
The buff tooltip is a reference to a verse from the poem "Paul Revere's Ride" (1860) by American poet Henry Wadsworth Longfellow: "One if by land, Two if by sea".
It appears to be a reference to World Of Warcraft, resembling the dragon turtle racial mount for the Pandaren.