Quest query - Up for a bit of fishing

Heya new to the beta, and came across this quest - "Up for a bit of fishing?" - all is great with it except one thing that's bugging me. On the 'red' island there is a chest to be claimed, however I haven't found a way to get at it. :( My tiremes managed to kill the guard, but I can't seem to figure out how to get over there. No paths across the river like in some other quests and no way to make transport ships.

Am I missing something? :D

Ty in advance

|||To get to the treasure on the island you need to have unlocked the "merchant transport ship" with the points you get forlevellingup your home city.|||that or use consumable mercenary units
|||Cheapest way would be the Recon Man consumable that spawns a scout.. costs 3 gold to buy..