If you’re in the Amsterdam, Muiden, or Naarden area then a great day trip is to the island Fort Pampus, part of a 19th century line of defence around the capital city of Amsterdam. You can take the ferry from Muiden or, better still, visit in your boat and moor up in their small harbour on the south side of the island.
There is 2m depth in the waters around the island, slightly less in the harbour. Watch out for underwater obstructions close to the island. Private boats stop on the inside of the larger pier and it is not necessary to book. Mooring is free and tickets for the museum can be bought on site, or just visit the Pampus Pavilion cafe restaurant and explore the island. More information on https://www.pampus.nl
BOC member Juergen Huettel recorded his visit there as part of the 2022 Naarden rendezvous; watch his video here.