We are spending three days in sorrento and would definitely like to see the blue grotto during our stay. Do we need to book in advance or is service to capri/blue grotto so frequent we'll be able to make arangements there? Any recommendations?

I can't answer your question, but I can offer some advice that might be helpful. The Blue Grotto is not something you can visit on just any given time or date. This is due to the tides. So be sure to check the tides before you make the trip to Capri. I've been to Capri twice and both times I was unable to get into the grotto due to high tides.

Your hotel in Sorrento will be able to tell you if the seas are calm enough to see the Blue Grotto. But - even if not I would still do Capri - there is no much more to see and do.

There are boats, hydrofoils (I think) to Capri on a frequent basis. Again, your hotel there will have exact times.

To get to the grotto when you land at the Capri Marina you take a motor launch that goes part way around the island to the area of the grotto. there you transfer from the launch to row boats (nothing larger can get in the grotto) and the oarsman will have you lay down in the boat - with your arms inside - to be sure you're not hurt going through the entrance passage. Once inside you can sit up again. After the tour of the grotto the oarsman and the seaman on the motorlaunch will help you climb back up into the motor boat. (This is relatively simple unless you're VERY petite - or are not steady on your feet.)

Hi! I stayed in Sorrento for a few days a few summers ago and used that as my base from which to see Capri and Positano. It was great! Make sure you try the pasta dish that is the specialy there - it's called the "something something sorrento" - sorry! I forget the name! but you'll see it on the menus.

As for the blue grotto, there are a few ways that you can see it. I took a boat from the marina in Capri which took us over. It was a nice boat ride, but it got really hot and sunny with no shade, which I find a bit uncomforable (i'm very pale and very sensitive to the sun).

Another way to see the Blue Grotto is to take a bus from Capri - it's like 10 minutes - and it will take you right to the area where the grotto is and from there you can board a row-boat. This way is MUCH less expensive. I guess it depends on the kind of experience you are looking for.

I have no idea about the tides or anything, b/c when I went it was open so not an issue.

Have a great time!

Your five minutes in the Blue Grotto is not worth the time, money, sweat, overcrowding and ,possibly, sea sickness, that it takes to get you there. There are any number of grottoes around Capri that will make you much happier!!

There are lots of services from Sorrento to Capri. The boats are run by different companies so just go down to the harbour, look at the ticket offices to see the departure times, and buy a ticket for the one you want. A one-way ticket is better because you then have a bigger choice of sailings back.
Access to the Blue Grotto depends on the weather. The entrance is very low so the rowing boats can only go in if the sea is very calm (the tide in the area is not significant).
The motor boats from the Marina Grande at Capri offer cruises round the island even if it's too choppy to enter the Grotto. If the Grotto is open, you transfer from the motor boat to a rowing boat, then pay the admission fee for the Grotto.
There is a lot to see on Capri even if the Grotto is closed, and there's also the Grotta Smeralda (Emerald Grotto) near Amalfi.

concetta, You wrote that you would definitely like to see the Blue Grotto during your stay. Our family felt the same way last July.

One morning, the weather was clear, sunny and about 80 degrees F., so we asked the concierge at our hotel if it was possible to tour the Isle of Capri as well as visit the Blue Grotto that afternoon.

The arrangements were made and six of us boarded a very nice boat with an outboard motor. Vincenzo was our guide and as we rode around the island, he pulled into various other grottos including the Green Grotto where we swam. Of course, the Blue Grotto was the highlight and for some unspoken reason, we were allowed into the B.G. ahead of all the other boats waiting to enter. Once again, we were able to swim for a few minutes inside the grotto (very cool water).

This excursion took about 3 hours and the cost was 130 euro. This was our second trip to Capri, but this was the first time the weather cooperated and we were able to enjoy a boat, water and sun.

Thanks for all the responses.
I'm hopeful that the tides will cooperative with our plans. We'll be there in late July. When I visited Capri 25 yrs. ago I was on a group tour and everything was arranged for us. I'm aware of all the conditions, but this is not a sight I want my family to miss. Grazie tanto.

The tide rises and falls twice a day and the times of the tides are calculated years in advance. If it's high water in the morning, it will be low in the afternoon, and vice versa.
The main problem in getting access to the Blue Grotto is the weather which cannot be predicted. If the sea is choppy, it is not safe to enter the cave.
If you want to go into the Grotto, choose a day when there's no wind and the sea is calm.