Final answer:
Oceana is the environmental group that focuses on preserving and restoring marine and coastal ecosystems in the North Atlantic, Irish Sea, and North Sea.
Step-by-step explanation:
The environmental group that focuses its efforts on preserving and restoring marine and coastal ecosystems, particularly in the North Atlantic, Irish Sea, and North Sea is Oceana.
Oceana is a global organization dedicated to protecting and restoring the world's oceans. They work on various initiatives to combat issues such as overfishing, pollution, and habitat destruction.