When you join to independent clauses with a conjunction you stablishes the equality in this clauses, however in this case you can see that the clauses have a causal relation, it could be said If you don’t hold my hand, I will drown, in this case the best conjunction to put the clauses together is “or” “Hold my hand or I will drown.”
A) to analyse the theme in a piece of narrative writing
<span>Say first, for Heav'n hides nothing from thy view </span>