This study aims to explore the reality of the sanctuary (mikdash) mentioned in Exodus 15:17 in the world of the narrative of Exodus as it now stands. For this, five existing views are critically analyzed. The result shows that ‘heavenly sanctuary,’ ‘eschatological sanctuary,’ ‘land of Canaan,’ ‘Jerusalem Temple,’ and ‘Moses' Tabernacle’ all do not fit the contextual background or terms of the poem. Based on this criticism, a new alternative is suggested. That is the ‘Sinai mountain-sanctuary.’ It is a view that the mountain Sinai itself is functioning as a ‘sanctuary.’ This interpretation is firstly consistent with the spatio-temporal background of this poetic context. Secondly, it coincides with the structure of the text, where ‘sanctuary’ is set as complementary for explaining ‘mountain.’ Thirdly, it coincides with the description of ‘thy hands have established.’ Fourthly, the text of Exodus 19-24 confirms that understanding. Fifthly, the vividness of the Exodus narrative comes to life as it is. In the end, when the text is understood in this way, it is revealed hat this poem was sung by the Israelites who had just crossed the Red Sea as prophecy and promise about the upcoming Mount Sinai experience.