The stretch of Main Street between 9th and 11th Avenues has a concentration of casual seafood restaurants that run through the Shore menu competently: clam chowder, fish tacos, fried clams, lobster rolls, and grilled fish platters. Most places have outdoor seating, a bar, and a menu that does not require much deliberation. The quality is consistently decent rather than exceptional, but the atmosphere — beach-town casual, slightly loud, good for groups — is exactly right.
Expect queues at the most popular spots on summer Friday and Saturday evenings. Counter service is faster than table service if you are hungry and impatient. Most restaurants are BYOB-friendly or have a short beer and wine list. Cash is still accepted almost everywhere.