There is no single Krk coastline. Baška opens towards a broad bay and pale mountains; Punat gathers boats around a sheltered inlet; the western shore lends itself to slower waterfront days. Choose the coast for the day you want, rather than trying to collect beaches.
Stay long enough to notice the changing light. A morning swim and an evening walk can make the same waterfront feel like two places. For a boat outing, ask about the route, meeting point, return time and weather policy. The water is part of the experience, not a promise of conditions.