Can you help me find scriptural references to the idea we are like a drop or a wave in the ocean unaware that we are the ocean, or that in samadhi we become the ocean?
Ocean-River analogy has been preached in Upanishads.
From Mundaka Upanishad:
यथा नद्यः स्यन्दमानाः समुद्रेऽ स्तं गच्छन्ति नामरूपे विहाय ।
तथा विद्वान् नामरूपाद्विमुक्तः परात्परं पुरुषमुपैति दिव्यम् ॥ ८॥
II-ii-8: As rivers, flowing down, become indistinguishable on reaching the sea by giving up their names and forms, so also the illumined soul, having become freed from name and form, reaches the self-effulgent Purusha that is higher than the higher (Maya).
From Prasna Upanishad:
स यथेमा नध्यः स्यन्दमानाः समुद्रायणाः समुद्रं प्राप्यास्तं गच्छन्ति भिध्येते तासां नामरुपे समुद्र इत्येवं प्रोच्यते ।
एवमेवास्य परिद्रष्टुरिमाः षोडशकलाः पुरुषायणाः पुरुषं प्राप्यास्तं गच्छन्ति भिध्येते चासां नामरुपे पुरुष इत्येवं प्रोच्यते स एषोऽकलोऽमृतो भवति तदेष श्लोकः ॥ ५॥
VI-5: The illustration is this: Just as these flowing rivers that have the sea as their goal, get absorbed after reaching the sea, and their names and forms are destroyed, and they are called merely the sea, so also these sixteen parts (i.e. constituents) of the all-seeing Purusha, that have Purusha as their goal, disappear on reaching Purusha, when their names and forms are destroyed and they are simply called Purusha. Such a man of realisation becomes free from the parts and is immortal. On this point there occurs this verse
From Chhandogya Upanishad (In the context of Mahakavya Tatvamasi):
इमाः सोम्य नद्यः पुरस्तात्प्राच्यः स्यन्दन्ते पश्चात्प्रतीच्यस्ताः समुद्रात्समुद्रमेवापियन्ति स समुद्र एव भवति ता यथा तत्र न विदुरियमहमस्मीयमहमस्मीति ॥ ६.१०.१॥
एवमेव खलु सोम्येमाः सर्वाः प्रजाः सत आगम्य न विदुः सत आगच्छामह इति त इह व्याघ्रो वा सिꣳहो वा वृको वा वराहो वा कीटो वा पतङ्गो वा दꣳशो वा मशको वा यद्यद्भवन्ति तदाभवन्ति ॥ ६.१०.२॥
स य एषोऽणिमैतदात्म्यमिदꣳ सर्वं तत्सत्यꣳ स आत्मा तत्त्वमसि श्वेतकेतो इति भूय एव मा भगवान्विज्ञापयत्विति तथा सोम्येति होवाच ॥ ६.१०.३॥
VI-x-1-2: 'These eastern rivers, dear boy, flow along to the east and the western ones to the west. They rise from the ocean and merge in the ocean, and become that ocean itself. And there as these rivers do not know themselves as "I am this river, I am that river", even so, dear boy, all these creatures, having come from Being, do not know, "We have come from Being". And whatever these creatures were here, tiger or lion or wolf or boar or worm or flying insect or gad-fly or mosquito, that they become again.
VI-x-3: 'That Being which is this subtle essence (cause), even That all this world has for its self. That is the true. That is the Atman. That thou art, O Svetaketu.' 'Revered sir, please explain it further to me'. 'So be it, dear boy', said (the father).
A related verse is present in Bhagavad Gita:
BG 2.70 - Like how the ocean without getting overflowed remains unchanged [even] when water enters; Similarly those [persons] in whom desires enter from everywhere -- attain bliss; Not the one who desires subjects.
Above verse relates "Ocean" with the "self". A "desire" relates with a "water body". Like how the "Ocean" is full of water, similarly the true "self" is already complete (i.e. no desire to be fulfilled).
If you are not insistent for "Ocean-Drop" analogy in particular, then here is the verse which matches the description in the Qn:
BG 15.7 - Among the living world, the living being (jiva) is "My" (self's) eternal fragment only; It (fragment or body) keeps attracting 5 senses & mind as the 6th towards the material nature.
In BG 12.7, ocean is referred as a continued flow of birth & death. But that doesn't seem suitable for your Qn.
On a personal note I had this similar dream (may be hallucinatory) since childhood, about a huge current of water flowing with loud noise, followed by a small droplet merging into it from somewhere.
The wave and the ocean are one: Though there are numerous waves in the ocean, big and small, rough and gentle, they are all made up of the same material which, is water.
The other very common interpretation is - There is certainly the appearance of waves, as well as foam and spray etc. but these are all simply different forms that we have named specially. There is only water. Similarly, there is only Brahman
This is one of the popular analogy examples that serve to portray the Hindu spiritual teaching.
It means that one's own Self (atman) is identical in nature with Brahman- the two words relate to the same entity or reality.
कनकं कुण्डलत्वेन तरङ्गत्वेन वै जलं |
विनिर्णिता विमुढेन देहत्वेन तथात्मता || 72|| - Aparokshanubhuti
KanKam KudaLeNa TarNgaTveNA Vai Jalam
ViNirNita VimuDheNa DehaTvaeNa TaThaTmata>br>
just as gold is thought as ear-ring and water as waves , so the Atman etc. Here Adi Shankaracharya is saying exactly what you are looking for as Ref. Here he is showing oneness of Atman And Brahman with ocean and wave example.
Here You can Download PDF File The verse can be found on page no.40
मय्यखण्डसुखाम्भोधौ बहुधा विश्ववीचय: |
उत्पद्यन्ते विलीयन्ते मायामारुतविभ्रमात || 497 || - Vivekachudamani
MayyaKhandaSukhaMbhoDhyou Bhaudha VishwaVichay
UpaDdyaNte ViliYnate MayaaMrutViBhraMaat
In me the ocean of infinite bliss the waves of the universe are created and destroyed by the playing of the wind of the maya.
Here Adi Shankaracharya is calling self as infinite bliss , which is attribute of Brahman (supreme creator) and thus showing oneness of Atman And Brahman. And the feeling of difference between Self (atman) and Brahman is due to Maya only.
And Here Is the PDF where you can read the above shloka with english translation