At least two or three usable batteries for your main camera, and more if you shoot a lot of video or run a power-hungry mirrorless system. Cold reduces battery performance temporarily, so keep spares in a warm inside pocket and rotate them through the day. Start every excursion with a full battery, because you can't count on charging between outings.
Use original or reputable batteries and test them before you travel. A cheap battery that fails or misreports its charge is not a bargain on a remote expedition. Label them and rotate so each gets used, rather than discovering mid-trip that an old one no longer holds charge.
The same applies to your phone. Keep it in an inside pocket when you're not using it, and keep the power bank warm too, because a cold power bank underperforms as well. Airplane mode helps when there's no usable signal to hunt for.
Charging aboard is usually possible but don't assume unlimited outlets or compatibility. Some ships prohibit power strips with surge protection, so ask your operator before packing one.