Rishi: Vājasaneyin transmission (ṛṣi attribution varies; often treated as cosmological yajus adapted from older strata)
Devata: Agni (as born of waters) / altar-body as Agni
Chandas: Tr̥ṣṭubh-like cadence (ṛgvedic-style cosmological diction)
Samhita Patha (Devanagari)अ॒पां पृ॒ष्ठम॑सि॒ योनि॑र॒ग्नेः स॑मु॒द्रम॒भित॒: पिन्व॑मानम् । वर्ध॑मानो म॒हाँ२ आ च॒ पुष्क॑रे दि॒वो मात्र॑या वरि॒म्णा प्र॑थस्व
Transliterationapā́m pṛṣṭhám asi yónir agnéḥ samudrám abhítaḥ pinvámānam | várdhamāno mahā́n ā́ ca púṣkare divó mā́trayā varímṇā práthasva ||
Translationநீ நீர்களின் மேற்பரப்பு; அக்னியின் யோனி; எல்லாப் புறங்களிலும் பொங்கிப் பெருகும் சமுத்திரம். மகத்தாக வளர்ந்து, தாமரையிலும்—வானின் அளவினாலும், பரப்பின் விரிவினாலும்—பரவுவாயாக.
Padapatha (Word Analysis)अपाम् । पृष्ठम् । असि । योनिः । अग्नेः । समुद्रम् । अभितः । पिन्वमानम् । वर्धमानः । महान् । आ । च । पुष्करे । दिवः । मात्रया । वरिम्णा । प्रथस्व ।
Word by Wordअभितःaround, on all sides पिन्वमानम्being made to swell/being filled वर्धमानःgrowing, increasing आforth, towards (intensively) पुष्करेin the lotus/pond (pushkara) वरिम्णाby breadth/expanse प्रथस्वspread out, expand 
Entities MentionedB
Brahman (as first principle) Viniyoga (Ritual Application)