The ‘Seahorse' coin is only legal tender in Portugal and has the following features:
On the obverse:
- Filling the centre, a couple of seahorses in their habitat;
- At the top, to the left, the name of the author and the words ‘Casa da Moeda’;
- At the top and in the middle, the face value and the Portuguese coat of arms.
On the reverse:
- A close-up of a seahorse surrounded by seagrass and seaweed;
- Around the upper edge, the words ‘Cavalo-marinho’ and ‘Portugal 2021’.
The issue limit was set at 25,000 coins with normal finish.