No, roaming is not free in Bermuda with US (AT&T/T-Mobile/Verizon) or UK SIM cards; expect high "Rest of World" international rates.
This is a common roaming trap for travelers. While your US or UK SIM card from carriers like AT&T, T-Mobile, Verizon, Vodafone, or O2 will likely connect to a network in Bermuda, it is crucial to understand the cost. Bermuda is explicitly not included in most EU, UK, or US domestic mobile plans, and it's often excluded even from "Caribbean" roaming packages. Your home carrier will almost certainly charge you their highest "Rest of World" international "Day Pass" rates, which typically range from $10 to $15 per day for basic usage.
This means that even checking emails or using maps for a short time can quickly become very expensive. For reliable and affordable cell service in Bermuda, consider alternatives. A eSIMBuy eSIM offers a one-time prepaid fee, providing a significantly cheaper solution for staying connected without the worry of unexpected daily roaming charges.