Herm is an island measuring 1½ miles north-south by half a mile east-west, so it's the smallest of the publicly-accessible Channel Islands. It's part of the Bailiwick of Guernsey and lies 3 miles east of that island. The population is about 65 - the Census of 2021 recorded 87 on Herm combined with Jethou. Little has ever happened here, even during the wartime occupation. Notable past residents were the novelist Compton Mackenzie, and Prince and Princess Blücher of Prussia: the Prince, descended from the ally who saved Wellington's skin at Waterloo, decided that what Herm needed was lots and lots of wallabies.
The only public transport to Herm is the Trident Ferry from St Peter Port on Guernsey. This sails daily year round, taking 20 min, with six sailings Apr-June and Sept-Oct, eight July-Aug, and only one Nov-March. In 2022 an adult return is £16, child £8, no charge for dogs. Buy tickets before boarding from the ticket kiosk, prominent next to the Weighbridge clock tower and roundabout on the Esplanade. (Or online, but that's only necessary if you need to be on a specific sailing, the ferry carries 70.) Listen carefully to their instructions for boarding and return, because these vary with the tides and weather. In St Peter Port it's usually the Inter-Island Quay a little further down the pier on the right, but at low tide it may be from next to the Weighbridge (the "Cambridge Steps" are no longer used). On Herm, it will be the main harbour at high tide, or Rosaire steps half a mile south at low water.
Walk. There are no vehicles on Herm, not even bikes. Locals use tractors and quads as necessary, and if you arrive with luggage for a stay-over, your accommodation can arrange a pick-up from the harbour. Spine Road is the bosky lane running the length of the island.
Ship Inn and Mermaid Tavern are the obvious choices.
The local family firm runs all the accommodation on Herm: the hotel, self-catering, and campsite.
The dialling code for Herm and Guernsey is +44, same as for mainland Britain and Jersey, so to call between them you don't dial +44. It's as if the entire Bailiwick of Guernsey was a mainland city with dialling code 01481 and UK domestic call charges.
Herm has 4G from each of its three carriers: Airtel-Vodafone, JT and Sure. As of Sept 2022, there are many dead areas towards the north and south of the island, and 5G has not arrived here. For the latest detailed coverage see GCRA (dead link: January 2023), as Nperf doesn't track coverage in the Channel Islands.
Visitors from the UK and Europe should check their mobile provider for roaming charges.
You must have personal travel health insurance: like the rest of the Bailiwick of Guernsey, Herm has no reciprocal agreements with the UK National Health Service, EU "EHIC" system, or any other nation. Any local medical treatment must therefore be paid in full.
Back to Guernsey it must be.