Howth's Cliff Walk
I only discovered this one recently and completely by chance. Of course I knew about the Howth summit for a while and have been around there many times. There's not lots of parking around so plan ahead. There is a map at the entry and there are 4 routes available. They all vary in length of time so it all depends on how much stamina you and your pupper have! Needless to say the walk has amazing views over the Dublin bay and the ocean is by your side on almost all routes.
Bull island
There are two ways to get to this beauty, from Raheny side on the North and on the Clontarf side via the wooden bridge. Parking gets quite busy but the walks around there are great especially around the sand dunes. Make sure you're aware of the nesting periods of birds around there and keep your dog on the leash to avoid any mishaps. The beach near the bridge has a great cafe there called Happy Out and is very popular with kite surfers.
Portmarnock beach
Arguably the prettiest beach in Dublin. This beautiful 5 km beach of velvety sand is backed by sand dunes which lead onto the Portmarnock golf course. These dunes are an important home to a variety of flora and fauna. It gets very busy when the weather is nice so parking can be a challenge. Make sure you familiar yourself with the area before heading off so you don't end up getting stuck in traffic.
Burrow Beach, Sutton
This sandy 1.2 km beach spreads out along the north side of Sutton and connects it to Howth head to the mainland. It's very simple to reach both by car or by public transport. And if you happen to be there on Friday afternoon or evening, you have to stop at Man Street Kitchen at Sutton RFC for some seriously good food. Make sure you order in advance though, they've become VERY popular :)
Paddy's Hill, near Portmarnock
One of my clients recommended this one recently and it didn't disappoint. Apart from the carpark there's no distractions around so you can have a peaceful walk enjoying the stunning views.
If you have any suggestions let me know, I'm always up for a new walking adventure!