Malahide Castle is 0.7 mi (1.2 km) from central Malahide, why not stop by during your stay.
If want to top up your tan, you might want to head out to Malahide Beach, located 0.6 mi (0.9 km) from central Malahide. If you want to continue walking by the waves, head to Portmarnock Beach and Donabate Beach.