La Concha: This is the postcard beach, that one with its beautiful shell shape that you must have seen...that same one that disappears when the tyde goes up, and that is usually frequented by the stylish locals, be it young or forever young. You will spot a numerous amount of extra tanned grandmas, who you can bet with who will end the summer with a better tan, but hey...you lost already. The western end of the beach is usually calmer, so you can set your towel there to spend the day underthe sun, and head back to the hostel in 5 minutes.
Zurriola: This is the‘Surfing’ beach in Gros. Big and full of young people, it is a very active and sporty beach, with excellent waves for surfing and nets to play volley ball at its eastern part. You might spot the random naked sunbather on its western end, who you can join if you want to get an average tan, and some fresh air! Waves are kinder in this side, so if Kelly Slater and his kind are not your heroes, go have a bath at this end! Zurriola is the perfect spot (specially the eastern end) for a beer, a bokata (sandwhich) and the sunset.
Ondarreta: In the western side of the city, and reachable after a pleasant walk by the seafront promenade, it is located right next to the “Comb of the Wind” (Peine de los Vientos) sculpture by Chillida. Some consider it just an extension of La Concha, and it is usually packed with families and a more elegant crowd. Nice to swim to the island or the diving boards and slides set in the bay.