Introduction
Pirate Coins and Sea Coins like Gienah's Coin and Procyon's Coin are extremely important to collect. They have various uses including, but not limited to, Ship Upgrades, Upgrade Materials, Enlisting Crew, Island Tokens, Giant's Hearts and Masterpieces. This guide will detail the various sources from which you can acquire these coins.
Pirate Coin Sources
Island Quests
Many Island quests themselves reward Pirate Coins. To check which Islands reward you Pirate Coins, check out Maxroll's Island Tool and filter for rewards.
Una's Tasks
There are 8 
Una's Tasks that reward you a considerable amount of Pirate Coins. A few of them also reward Harmony Leap Stone, and Great Honor Leapstone so you don't waste efficiency by focusing on these Una's Tasks.
A Hard Day at Work - Peyto
(Requires
The Future Is in Our Hands Completed)
10/10 ➜ Pirate Coins x2,000
30/30 ➜ Pirate Coins x6,000
50/50 ➜ Pirate Coins x10,000
80/80 ➜ Pirate Coins x16,000
Ride Like the Wind -
30/30 ➜ Pirate Coins x6,000
60/60 ➜ Pirate Coins x12,000
120/120 ➜ Pirate Coins x24,000
Playing by the Pirate's Rules - Hypnos's Eyes -
(RequiresHypnos's Eyes Quest Chain Completed)
20/20 ➜ Pirate Coins x17,000
30/30 ➜ Pirate Coins x19,000
50/50 ➜ Pirate Coins x36,000
Pest Control - Blackfang's Den -
(RequiresCatch the Rats Completed)
30/30 ➜ Pirate Coins x6,000
40/40 ➜ Pirate Coins x8,000
80/80 ➜ Pirate Coins x16,000
Crook Catcher - Runaways Island
10/10 ➜ Pirate Coins x2,000
50/50 ➜ Pirate Coins x10,000
100/100 ➜ Pirate Coins x20,000
For the Fermata's Maintenance - Fermata
(RequiresFor a Bigger Fermata Completed)
30/30 ➜ Pirate Coins x7,000
40/40 ➜ Pirate Coins x10,000
80/80 ➜ Pirate Coins x19,000
Bleak Night Fog -
30/30 ➜ Pirate Coins x7,000
40/40 ➜ Pirate Coins x10,000
50/50 ➜ Pirate Coins x12,000
She Drifts, Sea Gifts -
50/50 ➜ Pirate Coins x12,000
80/80 ➜ Pirate Coins x19,000
120/120 ➜ Pirate Coins x29,000
Procyon's Compass
Doing the 
Islands that spawn during Procyon's Compass can also reward you High Seas Coin Chest and Pirate Coins.
Exchange Merchants
At each region port, you can exchange Gienah's Coin and Procyon's Coin for Pirate Coins at 
Tea and Libra Guild Vessels.
Sea Coin Sources
Island Quests
Many Island quests themselves reward High Seas Coin Chest. To check which Islands reward you High Seas Coin Chest, check out Island Tool and filter for rewards.
Procyon's Compass
Doing the Islands that spawn during Procyon's Compass can also reward you High Seas Coin Chest and Pirate Coins.
Voyage Cooperative Missions
Each evening, 
Voyage Cooperation Missions reward around 300-400 Gienah's Coin and Procyon's Coin without factoring in the random key drops like Gienah's Key or Procyon's Key depending on the region the mission takes place. You can then use those Keys to open the chest, which spawns at the end of the Voyage Cooperation Missions.
Voyage Cooperative Mission Schedule
Cooperative Missions occur every day at 3 specific times near specific regions and usually consist of multiple chained events. The first Cooperative Mission that reward Gienah's Coin or Procyon's Coin typically starts near the harbor of a city. Check the in game calendar for “Ocean Co-op:...” to find the starting time and location of each event.
Summary
- Certain Island quests reward both Pirate Coins and Sea Coins like Gienah's Coin and Procyon's Coin.
- Certain Una's Tasks allow you to gather Pirate Coins without sacrificing gear progression efficiency.
- Sea Cooperative Missions reward Sea Coins, but only spawn during specific times. They also drop Gienah's Key or Procyon's Key which allow you to open a chest for additional rewards.
Credits
Written by Yaen