Beside all this (εν πασ τουτοις).

In all these things (or regions).

Gulf (χασμα). An old word from χαινω, to yawn, our chasm, a gaping opening. Only here in the N.T.

Is fixed (εστηρικτα). Perfect passive indicative of στηριζω, old verb (see on Luke 9:51). Permanent chasm.

May not be able (μη δυνωντα). Present middle subjunctive of δυναμα. The chasm is there on purpose ( that not , οπως μη) to prevent communication.