By cruising while fishing up a treasure, you can continue moving while opening the chest. This only works on the japanese version.
The grappling hook will automatically go up again if your speed goes higher than 3. But if you grab the treasure when your speed is lower than 3, the extra frame of cruising will allow you to cruise at up to 3.2 speed while fishing the treasure. This is mostly a small movement timesaver as this allows you to move towards your next destination during a cutscene.
This trick also permits going further with KoRL than where you are supposed to. By using this trick and then waiting on the reward textbox for a long time, you can even perform Greatfish Early.