There are so many different methods you can use when fishing in the sea. Plus the size of the fish can vary significantly, so you really do need to have the right type of reel to suit the type of sea fishing that you will be doing.
If you are going to be doing some lure fishing in an estuary or harbor, then you will not want, or need a really big and heavy reel. You will need one of the lighter spinning reels, that are designed for this kind of fishing, and the light weight of them will allow you to throw lures for a long time without becoming fatigued.
There are many different spinning reels to choose from, so you should always be able to find one that best suits your needs, and your budget. If you want to spend a bit more and get yourself a really good quality spinning reel, then something like the Shimano Stradic Ci4+ is a very popular choice.
Reels for boat fishing
Boat fishing is very popular, and when you go out into deeper waters you can expect to be targeting bigger fish. This will require a reel that is bigger and stronger than the smaller sized spinning reels mentioned above.
You can look at some of the bigger reels like the Shimano Stella range. This is a very expensive reel, but is used by many experienced fishermen who want to use the best and most reliable equipment.
Or if you are fishing deeper, then you may want to use an overhead reel. These are able to accommodate more line, and are easier and stronger to use when pulling in bigger fish. These types of reels are often used when fishing for big pelagic fish.
There is basically a type of reel for every kind of sea fishing these days, so you really should be able to get yourself one that is perfect for the fishing you will be doing. You can also find some very good fishing reels on a budget too, if you are not ready to spend bigger money of a reel just yet.