IEC EN 60529 describes various levels of system ingress protection against both water and dust.
IP*7 and IP*8 are sealing ratings for a system fully immersed under water.
IP*7 is precisely defined as immersion to a depth of 1 meter for 30 minutes.
An IP*8 rating indicates that the system remains dry after immersion to a depth > 1m and/or duration >30minutes. It is the intention of the standard that the time and depth of the test should be agree between customer and supplier according to the requirements of the application.