STCW Basic Safety Training, Personal Survival Techniques (PST) - STCW Code A - VI/1-1. 

STCW Basic Safety Training (STCW 78 as amended / 2010) certificates are a requirement for virtually all professional seafarers, who must be trained in compliance with the STCW convention.
If you want to work on a yacht, commercial ships and cruise liners the STCW BST certificates are mandatory and essential.
You need a STCW Basic Safety Training Certificate before you apply for a job.
If your STCW BST certificate is expired and older than 5 years you need mandatory Refresher Training.