Where is the location of 'plugins' directory for eclipse mars in mac OSX?

Eclipse Mars on the Mac has been reworked to be a proper Mac application with everything included in the Eclipse.app package.

The new path for the plugins is

/Applications/Eclipse.app/Contents/Eclipse/plugins

If you are looking at '/Applications' using the Mac Finder you will just see 'Eclipse'. You have to right click on 'Eclipse' and choose 'Show Package Contents' to see the contents.

Just putting things in the Eclipse plugins directory may not work. If at all possible you should use a proper Eclipse update site (sometimes called a repository) with 'Install New Software'.

Note most Eclipse installs now use 'oomph' which installs in a different location - see this answer

In my case (Mars on Mac version Darwin 14.5.0, installed with Eclipse installer) I found the plugins folder in MY_HOME_DIRECTORY/.p2/pool/plugins . I found this path with this: Eclipse -> About Eclipse -> Installation Details -> Configuration -> property --launcher.library