Śrī Rādhā is the ocean of amṛta cchabi rūpa.

She is the very form of glowing nectar and Her form is like a vast ocean.
She is mahābhāva personified and mahābhāva is compared to nectar. It is the deepest possible love for Kṛṣṇa, and Rādhā’s form reveals this beauty and tastefulness to the utmost, therefore She is the amṛtacchabi rūpa sindhu.
Although Śrī Kṛṣṇa inundates the world with a mere drop of His beauty, even He drowns in the nectar-ocean of Rādhā’s form!

Kṛṣṇa says in ‘Caitanya Caritāmṛta’ (Ādi 4, 242 243):

koṭi kāma jini rūpa yadyapi āmāra; asamordhva mādhurya sāmya nahi yāra
mora rūpe apyāyita hoy tribhuvana; rādhāra darśane āmāra juḍāya nayana
………………………………..
eimata jagatera sukhe āmi hetu; rādhikāra rūpa guṇa āmāra jivātu

“Although My form defeats millions of Cupids, is unrivalled in its sweetness and pleases all the three worlds, My eyes are still pleased by seeing Rādhā….In this way I am the cause of joy to the world. But Rādhikā’s form and attributes are My very life!”

Because the ocean of Rādhā’s form is so sweet it is compared to the second cosmic ocean, the ocean of sugarcane juice. (6)