The icon above of Pascha depicts Christ, having descended into hell and conquered death by death, standing on the broken gates of hell with its now useless keys, as He tenderly raises Adam and Eve, with patriarchs and kings. This particular icon is from the 15th Century, in Novgorod, Russia.
In the Orthodox Church the feast of Easter is officially called Pascha, the word which means the Passover. It is the new Passover of the new and everlasting covenant foretold by the prophets of old. It is the eternal Passover from death to life and from earth to heaven. It is the Day of the Lord proclaimed by God's holy prophets, "the day which the Lord has made" for his judgment over all creation, the day of His final and everlasting victory. It is the Day of the Kingdom of God, tile day "which has no night" for "its light is the Lamb" (Rev 21:22-25).
The celebration of Easter in the Orthodox Church, therefore, is once again not merely an historical reenactment of the event of Christ's Resurrection as narrated in the gospels. It is not a dramatic representation of the first Easter morning." There is no "sunrise service" since the Easter Matins and the Divine Liturgy are celebrated together in the first dark hours of the first day of the week in order to give men the experience of the "new creation" of the world, and to allow them to enter mystically into the New Jerusalem which shines eternally with the glorious light of Christ, overcoming the perpetual night of evil and destroying the darkness of this mortal and sinful world:
Shine! Shine! O New Jerusalem! The glory of the Lord has shone upon you! Exult and be glad O Zion! Be radiant 0 Pure Theotokos, in the Resurrection of your son!
This is one of the main Easter hymns in the Orthodox Church. It is inspired by Isaiah's prophecy and the final chapters of the Book of Revelation, for it is exactly tile New Creation, the New Jerusalem, the Heavenly City, the Kingdom of God, the Day of the Lord, the Marriage Feast of the Lamb with his Bride which is celebrated and realized and experienced in the Holy Spirit on the Holy Night of Easter in the Orthodox Church.
[Above is from the OCA's page on Holy Pascha.]