SB 11.8.5

muniḥ prasanna-gambhīro
 durvigāhyo duratyayaḥ
ananta-pāro hy akṣobhyaḥ
 stimitoda ivārṇavaḥ
Synonyms: 
muniḥ — a saintly sage; prasanna — pleasing; gambhīraḥ — very grave; durvigāhyaḥ — unfathomable; duratyayaḥ — unsurpassable; ananta-pāraḥ — unlimited; hi — certainly; akṣobhyaḥ — not to be disturbed; stimita — calm; udaḥ — water; iva — like; arṇavaḥ — the ocean.
Translation: 
A saintly sage is happy and pleasing in his external behavior, whereas internally he is most grave and thoughtful. Because his knowledge is immeasurable and unlimited he is never disturbed, and thus in all respects he is like the tranquil waters of the unfathomable and unsurpassable ocean.
Purport: 

Even in the midst of great distress, a self-realized sage does not lose control of himself, nor is his spiritual knowledge lost. Thus he is akṣobhya, or undisturbed. His mind is fixed on the Supreme Personality of Godhead, who is the reservoir of unlimited spiritual bliss, and having linked his consciousness with the supreme consciousness, his knowledge cannot be measured. A pure devotee, having taken shelter of the Lord’s lotus feet, possesses great spiritual power, and therefore he cannot be surpassed or overwhelmed. In fact, having developed his spiritual body, he is not affected by the deteriorating actions of time. Although outwardly he is friendly and pleasing to everyone, internally his mind is fixed in the Absolute Truth, and no one can understand his actual purpose or plan. Even the most intelligent human being cannot understand the mental activities of a self-realized devotee who has given up material life based on lust and greed and taken shelter at the lotus feet of the Lord. Such a great soul can be compared to the mighty ocean. Innumerable powerful rivers plunge into the ocean, but the ocean remains calm and peaceful. Thus, a saintly person is understood to be, like the ocean, pleasing, unfathomable, grave, unsurpassable, unlimited and unshakable.