That little phrase comes from the Prayer Book collect for an Ember Day:
"Almighty God, the giver of all good gifts, who of thy divine providence hast appointed divers Orders in thy Church: Give thy grace, we humbly beseech thee, to all those who are to be called to any office and administration in the same; and so replenish them with the truth of thy doctrine, and endue them with innocency of life, that they may faithfully serve before thee, to the glory of thy great Name, and the benefit of thy holy Church; through Jesus Christ our Lord. Amen."
(It of course refers to diversity, rather than to those who go under the sea and swim!)
I have, in days of yore, tended to think of these as the 3 orders of Ministry (Bishop Priest and Deacon) with the additions of professed religious (also a Vocation) and Lay Readers (all too often in the past a consolation prize for those who didn't pass selection conferences). But as I get older and a little bit wiser, I realise that that diversity can apply to anyone who does their job or fulfills there calling to serve and enable the kingdom. Preaching sermons or wiping bottoms - all are part of God's plan of "divers orders". All need replenishing with truth and innocency of life if they are to continue to function well as servants of the Most High. So a wee prayer for all who serve, however they serve to day seems appropriate.