Here is the full list of all 17 Aqua Moto Racing Utopia trophies - there are 3 bronze, 4 silver, 9 gold and 1 platinum.
Complete all other Trophies
Find the ball of straw at each Venue
Own every watercraft
Perform every water stunt at least once in a Freestyle Event
Perform a Backflip with a Runabout watercraft
Perform every stunt at least once in a race
Perform every air stunt at least once in a Freestyle Event
Win the gold medal in all Freestyle events
Win gold medals in Time Trial mode on every Track
Complete the tutorial
You must pass each buoy perfectly in a Championship race
Perform 20 stunts during a Freestyle Event
Win every Ski Championship
Win every Runabout Championship
In a Championship race, pass every buoy in 1st place and win
Jump over 40m
Win a Championship event