Where the Blue Grotto is, and the three ways to reach it

Which boat, and from where?Every option below still leaves the €18 at the cave to pay on the spot. What changes is where you sail from and how long the day is.
Compare all sevenThe one thing to grasp about the geography
The cave opens at sea level on a stretch of coast with a cliff above it. The road from Anacapri gets you to the top of that cliff and no further. From there a flight of stairs goes down to a small landing on the rocks, and from the landing a rowboat takes you the last part. Coming by sea, the motorboat brings you to the same spot and you make the same transfer, except that you wait offshore rather than on the steps.
So the choice is not really boat against bus. It is where you want to spend the wait, and whether you want to pay €23 to €25 for a sea crossing you could replace with a €2.40 bus ticket. I do not think there is one right answer to that, but I do think most people make the choice without knowing there was one.

By motorboat from Marina Grande
The boats leave from Molo 0 and Molo 21 at Marina Grande; a third company also runs the route. Two different products leave from those piers and they are easy to confuse. A transfer-only boat runs about an hour and takes you to the cave and back, which is what guarantees you the stop. An island tour runs about two hours, circles Capri, and may skip the grotto stop entirely if the wait there is long. Realistically I would set aside two hours for the transfer version once the queue is counted, not one.
The money, in order: €23 to €25 for the return motorboat, then €12 for the rowboat, then €6 for the state entrance ticket. That is €41 to €42, and almost nobody publishes it. The motorboat is a transfer and nothing else — it does not include the cave, and no ticket exists that covers both. The full breakdown sits on what it costs in total.
By bus from Anacapri
Staiano Autotrasporti runs the Anacapri to Grotta Azzurra route. The fare is €2.40 bought in advance and €2.90 on board, and a day pass is €7.50. The stop is Piazza della Pace. Capri’s own tourism site gives Viale De Tommaso instead, which is the ATC terminal, and the two get mixed up often enough that I would leave yourself a few minutes to ask somebody rather than sprint to one of them. Published journey times run from five to fifteen minutes depending on which source you read, which tells you how much traffic varies.
A taxi from Piazza Vittoria takes roughly ten minutes. From the road, the stairs go down to the landing. Budget an hour and a half to two hours from the centre of Anacapri including the queue, and treat that as a budget rather than a timetable — no source I trust publishes a round-trip figure for the land route, so I will not print one as if it were measured. The step by step version is on going without a tour.
On foot
It is 3.5 km from Anacapri, 40 to 50 minutes, and every published figure for it describes the walk downhill. That matters, because the same 3.5 km back up in August at two in the afternoon is a different proposition entirely, and there is a bus. I know people who walk down and ride up, and I think that is the sensible version of this idea.
Queue on land, not at sea
Whichever way you arrive, you join the same rowboat queue. The difference is your footing. From land you wait on the steps; from the sea you wait bobbing in a small boat offshore, sometimes for an hour or more. Even capri.com, which sells the boats, advises people prone to seasickness to queue on land. If that is you, the bus is not the cheap option, it is the correct one.
Before you set out at all
Check whether the cave is open. The mouth is about a metre high above the water, so any swell or onshore wind closes it, and the decision is made at the cave mouth at nine in the morning. the Motoscafisti open/closed banner carries a dated open or closed line, updated daily and syndicated across the island sites, and there is a phone number, +39 081 8375646, that works after 9am. A closed morning costs you nothing at the cave, since the €6 and the €12 are paid there. It costs you the bus fare, or the transfer, or the tour. Hours, and why it closes, has the whole picture.
If you are coming from the mainland
Then the ferry and the island are the day, and the grotto is a stop inside it. The four departure points sold as day trips are Sorrento, Naples, Positano and Capri itself, and they are compared on boat tours to the grotto. Every one of them still leaves you the €18 to pay at the cave, because none of them includes entry.
CheapestCapri: Island Boat Trip with Grottos
Best ratedSorrento: Exclusive Capri Boat Tour and Optional Blue Grotto
From NaplesFrom Naples: Capri, Anacapri, and Blue Grotto Full-Day Trip
Frequently asked questions
Where is the Blue Grotto in Capri?
On the north-west coast of the island, below Anacapri, at sea level under a cliff. No road reaches the water. You get there by motorboat from Marina Grande, or by Staiano bus or on foot from Anacapri followed by a flight of stairs down to the rowboat landing.
How do you get to the Blue Grotto from Capri town?
Down to Marina Grande and out by motorboat from Molo 0 or Molo 21, which is about an hour for the transfer alone and nearer two once you count the queue. The total is €41 to €42 per person — the three charges are broken down here.
How much is the bus from Anacapri to the Blue Grotto?
€2.40 bought in advance and €2.90 on board with Staiano Autotrasporti, or €7.50 for a day pass. It leaves from Piazza della Pace, though Capri’s tourism site gives the ATC terminal at Viale De Tommaso, so allow time to ask. Journey times are published as anything from five to fifteen minutes.
Can you walk to the Blue Grotto?
Yes, 3.5 km from Anacapri, 40 to 50 minutes, and the published times are for the downhill direction. Walking back up in summer heat is another matter, so plan to ride the bus one way. Timing it against the queue is easier in the shoulder months — the hour-by-hour pattern is here.