Regular three-hour cruises to Lysefjord and Preikestolen are run year-round by this experienced company. There are two daily cruises from Easter to September at 10am and 2pm, with an extra midday cruise in June, July and August. From October to April there's just one 11am cruise daily from Wednesday to Sunday. Tickets can be booked in advance online.
From May to September there's an option to add on the hike up to Pulpit Rock (adult/child 850/500kr). The ferry to Tau and the bus to the starting point at Preikestolhytta is included, as is the bus fare back to Tau, but you'll need to pay on board for the Stavanger–Tau ferry. All in all, it's an excursion of around eight hours, including the hike.