Here is the full list of all 43 Summer in Mara (EU) trophies - there are 20 bronze, 21 silver, 1 gold and 1 platinum.
Take care of Mara.
Pay the mortgage on your boat.
Complete all the quests from Napopo.
Visit all the islands from Mara.
Defeat the Elit.
Recover all the chrystalis from the Door.
Complete all the quests from Rigatta.
Complete all the quests from Pilly, Milly & Tilly.
Complete all the quests from Ecco.
Complete all the quests from Litio.
Complete all the quests from Blu.
Complete all the quests from Aquila.
Complete all the quests from Akaji.
Complete all the quests from Taima.
Beat Ereti in a race.
Complete all the quests from Mayo.
Get all the Koa's outfits.
Complete all the quests from Noho.
Complete all the quests from Caleb.
Complete all the quests from Awan.
Unlock all the crops on Home Island.
Complete all the quests from Onzo.
Use the recycle bin 100 times.
Get all the Koa's backpacks.
Get the boat to max level.
Sell objects for a total of 2500 coins.
Sell objects for a total of 1000 coins.
Complete all the quests from Taka.
Get one farm animal of each type for your island.
Complete all the quests from Brram.
Cook 30 dishes.
Meet Dunna.
Complete all the quests from Mûn
Carry 99 oranges in the backpack.
Unlock the mine.
Craft 40 objects.
Craft 20 objects.
Cook 15 dishes.
Remember...
Meet Saimi.
Collect 60 objects.
Wake up after the tutorial.
Collect 30 objects.