now, youve come across the "evil (crimson/corruption) biome" and you cant compete or just dont want to fight the literal hellspawns in those biomes but you want to cross it because you want to get to the ocean or out of curiocity, so what to do is:

dig a small hole just out of the evil biome and dig down and forth (right or left) with 1 block between your tunnel and the overworld wich makes the creatures unable to attack you (if it doesnt have any special ability wich i havent seen yet) and you can also open chests and destroy vases from your tunnel

if you come up on a tunnel or crimson/corruption stone just use dirt or any other block to build an artifical tunnel, you can build 2 or 3 blocks out and always close it so no enemy can get in, also works when you HAVE to get out of your tunnel, just make your artifical tunnel above