Here is the full list of all 36 Dead Island Riptide trophies - there are 20 bronze, 11 silver, 4 gold and 1 platinum.
Collect all other trophies
Complete all the main quests cooperatively with any number of partners
Kill 10 monsters with one mine
Mark 100 opponents which were then killed by your co-op partners
Finish the game
Find and kill all the most dangerous monstrosities located in dead zones
Finish all quests in the game
Find all collectibles
Obtain level 70
Kill 100 monsters using the boat's speed boost
Find all the volunteer's voice recordings
Find all pages from the guide book
Find all the secret files
Kill 100 enemies using charge attacks
Defeat Harlow
Enter the docks in Quarantine Zone
Finish hospital quests for Cecil
Make pact with Serpo
Survive the horde on the roof
Gain access to a long-range radio station
Find 50% of collectibles
Clear out the cinema
Finish quests for Dr. Kessler
Reach Henderson
Kill special enemies: Grenadier, Thug, Wrestler, Infected, Suicider, Screamer, Butcher, Floater.
Kill the Twins
Successfully defend the tunnel entrance
Install a total of 5 barricades during hub defense
Kill 100 monsters with thrown melee weapons
Rescue 20 NPCs that have been grabbed by monsters
Kill 25 monsters with a chainsaw
Find a boat for use in the jungle
Kill 100 monsters with a kick
Kill 50 monsters by smashing, decapitating or shooting them in the head
Obtain level 50
Escape from the ship