The theme of Tennyson's poem centers on the idea of maturation and growth. The journey that Tennyson articulates in the pom is one where courage and maturation are needed in order to effectively cope with the reality that lies outside the harbor, into the sea. The "bar" that has to be crossed lies in this voyage, and being able to understand that one might not be able to fully control it, but rather be able to accept it as a part of being in the world is where the poem's strength lies. The unknown, and what lies outside the realm of the harbor, cannot be tamed nor can it be avoided as all journeys enter "the boundless deep." This cannot be averted and is a part of the ship's purpose, and the journey of consciousness. Tennyson suggests that this is a phase that must be passed, with faith placed in the "Divine and Unseen Who is always guiding us.” In this, the poem's thematic application to death and dying becomes something that resonates throughout, making the poem so significant.
also consider that the stanzas are thematicly grouped ie the 1st n 3rd and the 2nd n 4th satnaza are giving same msg