Koh Samui is where essentially all of these tours begin. The shape of the day rarely changes: a van collects you, you check in at a pier, you sail, you stop at the islands, and the same van drops you back.
Zones and times are not identical across operators. Put your hotel in during booking so any surcharge shows up before you pay rather than after.
Boats leave from several different piers around the island. If your transfer is included this barely matters. If you plan to drive yourself, it decides both your alarm and your journey home.
The van collects a string of hotels, so your pickup can be a long time before the boat actually casts off. Keep your phone on you and stay where the confirmation told you to stand.
The van sweeps several hotels on one route, so the first pickup can sit forty minutes before the pier while the last one boards almost directly, and neither guest is treated unfairly because the order simply follows geography. Pier check-in includes a briefing and life-jacket fitting. Boats aim to depart in a fairly narrow morning window, which is why a missed pickup usually means a missed boat rather than a short wait for the next one, and why the phone number in your confirmation is worth saving the night before.
Hotels near the north and east coasts sit closest to most departure piers, so guests there tend to get the latest pickups and the earliest drop-offs, while stays in the south and west of the island add road time to both ends of an already long day. That is rarely a reason to change hotels. It is a good reason to order a breakfast box instead of queueing for the buffet on tour morning.
Compare every Ang Thong boat option, speedboat and big boat side by side.
From the covered zones, on most tours, yes. Out at a remote villa it may cost extra or you may be asked to meet the van at a nearby point.
Some operators are happy for you to turn up yourself. When that is allowed, the meeting point appears on the booking page.
These are full days. Expect to be back late afternoon or early evening, with the boat and the sea having the final say.