将来(jiāng lái) - the future, in the future in Mandarin

将来 (jiāng lái) is the future as a stretch of your own life: what you will do, where you will live, who you will become. It pairs naturally with 现在 and 过去.

Grammatically it is a time word, so it needs no preposition and it likes the front of the sentence: 将来我想住在海边. English forces in or in the future; Mandarin just puts the time first and moves on.

Two neighbours to keep apart. 未来 is the same idea pitched higher and wider, the future of a country or of technology, and it can modify a noun directly (未来五年). 以后 means afterwards, relative to some point already mentioned, so 我以后想住在海边 quietly implies after whatever we were just talking about.