Travellers who have plenty of time to spare might want to take the ferry to Anambas. It's quite an affordable means to travel, so it may be just the ticket for those on a tight budget, such as backpackers or students on a school break. But keep in mind that the journey takes 8 hours in the best of cases.
Should there be any weather along the way, or an agitated sea state, or, as is often te case in this area, both, then expect the journey to take 10 hours or more. This is still rather feasible sure, although this particular vessel isn't the most spacious; there's not a lot of disposable comfort for the passengers.
Also, no meals or drinks are served on board, so best BYO.
Additionally, the cabin aircon appears to be on its last legs, because it has a nasty habit of breaking down at some point during the trip.
Still, going by ferry is a great money-saver and it also gives you the chance to meet the affable locals shuttling to and fro. So, all in all, it can be a decent option for those not too bothered by the issues.
If you're planning on taking the ferry, it's good to know that it departs from Tanjung Pinang and has 2 stops: Letung and Tarempa. So if your accommodation booked is in Tarempa, make sure you don't disembark the ferry at the first stop, Letung. FYI, from Letung to Tarempa can be another 1.5-2 hours or so.
By the way, during the Letung stop, snacks and drinks are offered by a dozen or so enthusiastic villagers, who waste no time hopping aboard and cramming the ferry aisles, all the while touting their goodies. It all makes for a somewhat hectic affair, but it's good-natured and the snacks on offer, typically home-made, are absolutely delicious without fail.