The ark is the Church. The deluge is this life with all its cares and temptations. The animals are the different characters of men found in her (the church):
It should not frighten you that in the Church the bad are many and the good few. For the Ark, which in the midst of the Flood was a figure of this Church, was wide below and narrow above, and at the summit measured but one cubit (Gen. 6:16). And we are to believe that below were the four-footed animals and serpents, above the birds and men. It was wide where the beasts were, narrow where men lived; for the Holy Church is indeed wide in the number of those who are carnal minded, narrow in those who are spiritual. For where she suffers the morals and beastly ways of men, there she enlarges her bosom. But where she has the care of those whose lives are founded on spiritual things, the se she leads to the highest place; but since they are few, this part is narrow .... And so the more the wicked abound so much the more must we suffer them in patience; for on the threshing floor few are the grains carried into the barns, but high the piles of chaff that are burned with fire. - St. Gregory the Great (+ 604)
Similarly, - for almost everything that takes place in the Church is a type of the spiritual life of each individual - the ark is each person or rather a spiritually mature person. Someone who has labored in the practice of the commandment applying them both outwardly and inwardly. Ten times ten make a hundred - the years it that took to build the ark - and ten commandments squared make for the building of the soul (inner and outer man). The planks are of course the virtues, the animals are the beastly passions which are placed in the lower decks of the ark to signify their subjection to the mind - the human deck. The pitch that Noah used to pitch the ark is humility and sobriety, which protect the soul from the waters of the passions and especially pride (I hope you can see the relevance: pitch is black and sobriety is often associated with gloom). The dimensions of the ark reflect the trinitarian theology (300 and 30) as well as the confession that God is the creator of the world (50 for the senses), both indispensable for a structurally (read theologically) sound soul. There's more to those numbers when taken to represent the virtues but I do not have St. Maximus handy to quote his explanations (in this particular context). I only have an explanation for the number thirty (different context but applicable), which I quote below:
The Lord appeared when He was thirty years old, and with this number secretly teaches those with discernment the mysteries relating to Himself. For, mystically understood, the number thirty presents the Lord as the Creator and provident ruler of time, nature, and the intelligible realities that lie beyond visible nature. The number seven signifies that He is the Creator of time, for time has a sevenfold character. The number five signifies that He is the Creator of nature, for nature has a fivefold character because of the fivefold division of the senses. The number eight signifies that He is the Creator of intelligible realities, for intelligible realities come into being outside the cycle that is measured by time. And the number ten signifies that He is the provident ruler, because it is the ten holy commandments that lead men towards perfection, and also because the symbol for ten1 is the first letter of the name taken by the Lord when He became man. By adding up five, seven, eight and ten you obtain the number thirty. Thus he who truly knows how to follow the Lord as his master will understand why, should he attain the age of thirty, he will also be empowered to proclaim the gospel of the kingdom. For when through his ascetic practice he has irreproachably created the world of the virtues as if it were a world of visible nature, not allowing his soul to be diverted from its course by the hostile powers as he passes through time; and when he unerringly gathers spiritual knowledge through contemplation, and is providentially able to engender the same state in others, then he himself, whatever his physical age, is thirty years old in spirit and makes manifest in others the power of the blessings which he himself possesses.
In other words, the story of the ark is a summary of the "way of virtue," how to escape death and attain eternal life, how to avoid the passions and attain enlightenment: Tao te Ching.
PS. Of course - unlike rationalists and monotonic minds - we Orthodox do not exclude the literal, albeit miraculous, events concerning the flood, as well as other allegorical interpretations that the infinite wisdom of God has interwoven with the story and which are beneficial to meditative minds.
